Please publish the before and after dyno graphs.

 

Where did you read that Alf made dyno test?

Anyway, this point of view seems good, just one question: Does le OEM ECU is really able to manage properly fuel invrease and slip exhaust?

 

Dyno runs are not budget...

The stock ECU works flawlessy with this setup. In closed loop it deals with the increased air flow adjusting injector pulse duration to match the target AFR. In open loop (idle, accel transient and full throttle) the increased injector flow compensates for increased air flow to make more power.

You can estimate the injector flow needed knowing the power target after modifications. Knowing the stock injector flow you can calculate the increase in fuel pressure needed to match the desired engine power. I went deep on this post:

fuel injector flow rate

Hey, what is the fuel injector rated at for flow? What pressure if anyone knows that? I have searched, but so far nothing. thanks

www.ktmduke390forum.com

Yes, you need to get this Dyno proven, but the material and parts I used are well known and already tested. I'm not selling nothing.

Air flow is improved, exhaust flow is improved, lambda readings show no lean conditions: additional power is being made. Just as simple.


Regards.

 

Dyno runs are not budget...

That reminds me of my 80cc bike with I was young.
I changed the exhaust to a louder one and I can guarantee you it accelerated a lot faster.

 

I can confirm that the Coober airbox Lid DOES NOT work with the 390 ADV.
PT CANNOT compensate for the excess Air the open airbox lid pulls through.
I have spent the last 2 months with the PT manufacturers and the best solution was the stock airbox lid. HUGE difference in drivability and the cutting out issues I was plagued with.
The stock ECU can barely compensate for a slip on, let alone an air filter also. This has been my experience over the last 1200KM. YMMV.

 

Did you installed only the airbox lid??? Wich is your bike's configuration?

I agree ECU (stock or Piggyback aftermarket) alone can't compensate for air flow increase unless you have more fuel available. This can be achieved with larger flow injector or with higher fuel pressure regulator.

Lean conditions are not good to make power and make the engine prone to knocking. All we know knocking is the most destructive event in an engine. My recipe was always looking to minimize factors that induce engine knocking.

Thousands of hours were spent in the bench Dyno at Mattighoffen to set the stock ECU, so keep it is always a good option.

Regards.

 

Coober Airbox Lid, K&N Air filter, Akrapovic Powerparts Slip on.
The larger injectors or regulator are of no consequence if the ECU is unable to supply the required fuel in the first place.
The PT can do about 12% but even that is not enough for the bike. M2 is the same as M1 with rather significant Ignition advance.

 

The ECU can't overcome phisical lack of fuel. But once you have bigger injector or increased pressure ECU should work just fine. For example programmable ECU's as Megasquirt or Motec can run on almost every engine.

Too big injectors don't like too short pulses, so idling and closed loop can be an issue. Too high fuel pressure regulator can reduce pump's flow... So (as everything) is a question of finding a sweet spot... Whenever possible I prefer using increased fuel pressure instead of bigger injector, because increased fuel pressure improves fuel atomisation (better injector spray).

The stock ECU will not produce too much power when in closed loop: it will use lambda readings to adjust pulse duration of the injector to match the target AFR table (normally leaned for low emissions and low fuel consumption).

Using more ignition advance in timing maps when the fueling is still lean will certainly provoke engine knocking...

 

Sound doesn't make power. How many thousands of neighbours in a big city can be disturbed by just only one slip on idiot???🧐

you are quite right that sound doesn’t equal power but what it does do is save my life, when idiots in their steel box don’t use the mirrors that they should and have been trained to use (in the Uk) I couldn’t give a toss about the neighbours and what they think, I think about my life and through experience a louder pipe is often heard long before any look is given, hence why the emergency services have bloody loud sirens.

 

It should be a horn always available on your bike, may be you don't need to be noisy all the time...

 

About the 6205 spark plug, I can't find that it fits the KTM 390 Duke. Is that your empirical information? NGK parts finder only shows the stock spark plug as compatible with our bikes.

 

OK so let's get "EMPIRICAL"😁...

For Euro4 KTM engines (2017 & up) the stock sparkplug is Bosch VR6NEU. The equivalent (copper core) NGK sparkplug is LKAR8A-9.

When choosing sparkplugs for your engine the safer option is always stick to the manufacturer's recommendations, but if your bike is no more stock may be better change sparkplug specs. Considering:

1.- Sparkplug manufacturers use different scale to define heat rate. The intermedium number in the Sparkplug code is for heat rate (capacity to make combustion chamber heat drain to the head cooling water pockets). The longer ceramic insulator nose, the less heat exchange with the head water cooling pockets, the hotter rate of the spark plug.

For example Bosch and NGK have inverse heat range coding scale. See the chart:

2.- Is crucial to make sure that electrode protrusion on the chamber remains the same as original.

You can consult a cross reference chart or rely on quality information as this site:

KTM Spark Plug Fitment Chart

Intro Table of Contents KTM Spark Plug Fitment Chart ManufacturerModelStandard PlugIridium PlugElectrode GapKTM1050 ADVENTUREOuter LMAR7DI-10Inner LKAR9BI-101.0 MMKTM1090 ADVENTURE (EURO 4)Inner LKAR9BI-10Outer LMAR7DI-101.0 MMKTM1090 ADVENTURE R (EURO 4)Inner LKAR9BI-10Outer LMAR7DI-101.0...

bikerrated.com

3.- Spark plug gap between electrodes: the bigger the better. Wider gap increases the chance to ignite moisture passing fast and with turbulence. But too large gap can provoke spark plug ignition cable leaking. And the higher the compression (air dielectric resistance) and the gap, the higher voltage required to make the spark jumping across the gap. The higher the voltage the better and thicker cable isolation needed and so on... Stock ignition cable and boot can withstand 1.0mm gap.

The spark plug I used is the LKAR9BI9 @ 1mm gap wich is the NGK Iridium equivalent, two degree colder rate. The same dimensions "LKA" and also resistive "R" to avoid electromagnetic interference, "9" is two degrees colder (than stock) and "I" states for Iridium...

Iridium (electro erosion resistant) spark plugs last longer +50.000km and despite of Iridium being less conductive than copper (only the central electrode tip is actually Iridium, the rest is copper), it sparks better due to the reduced area of the tip wich concentrates the plasma discharge. Also the shape of the tip helps redirect air-fuel mixture to pass between the electrodes. As I said: Larger initial kernel, faster flame propagation: more complete fuel burn, less emissions.

Hotter spark plugs make engine prone to knocking (my recipe always keeping an eye on prevent knocking). As I live at sea level in a warm climate I went 2 degree cold (compared to stock) heat rate. Since I installed the LKAR9BI9, cold start was never an issue.

I should start another topic on this but I don't have a f****g Dyno on my garage (I'm trolling all of you)...🖕🏻🤣

Regards,

 

I'm more than convinced. I guess I was just asking about dimensions, but your explanation far exceeded that.

Is there an even "colder" spark plug fitting our bikes? like LKAR10BI9 or something?

 

Unless you go wild radical (turbo...), stick to 1 or 2 heat degrees colder from manufacturer stock spark plug or one degree hot.

Your engine is a thermic machine and draining too much heat from combustion chamber can reduce efficiency. Also too cold spark plugs can produce hard cold starts...

Hardly a hotter spark plug may be needed in case of high altitude and low air temperature. Also some turbo setup use hotter sparkplug. In a street bike going for hotter spark plug is ask for engine knocking...

Regards,
Alf

 

Please spend the money for the maintain or visual parts for duke 390.the bike is awesome as it is.if you wanna more performance go with duke 690

 

Now I got the performance I need for my 401 Vitpilen.

Additional counterweight crankshaft works fine in our 390's and 401's, but 690's and 701's engine is too big and too single...

 

I have been running the iridium plug meant for the rc390 for over 10,000 miles. It was more about not worrying about having to change it than anything. I would like to add that I am interested in the effects of the increased fuel pressure regulator. I am fully aware of how it works and the benefit that could come from it and I am willing to test it out.

I have over 20 data logs of various running conditions that show my AFRs. I am working on installing this once my gasket gets here and I'll see if it affects AFRS. I am hoping to get a little more fuel as I can't seem to get below a certain thresh hold at WOT. More to follow.

 

Nice!

Datalog lambda readings while running is a very good approach The stock lambda O2 sensor is narrowband so not too much definition from it.

In an ideal world with no budget restrictions, the best option will be welding a second bung on the exhaust header and use a wideband lambda to datalog...

Regards,

 

Mythbusters 390 edition! The results are in and Installation was super easy. The OEM fuel pressure regulator is set at 3 bar of pressure and this unit is 3.5 bar. Converting both to psi it shows a gain of 12% more fuel pressure (mathematically, not real world). I have concluded three things:
1. It seems that it might have an effect at low load - high rpm range.
2. Appears to have no effect at heavy load - wide open throttle.
3. I need to adjust my tune a little now that I live in a state that it's super cold all the time.
Overall, I didn't have much hope and I wanted to put to theory whether there were any benefits based on the forum post. I do not recommend this as it was not as beneficial as stated.
Gonna add this to the Myth section.

 

You have to bust considering apples with apples. If not, you are not busting, you are only dusting... 🤣

You don't say nothing about your bike's setup, but I deduce you have a programmable ECU (piggyback or standalone).

1.- If you already had right amount of fuel at WOT (high load), increasing fuel line pressure won't provide any additional performance (unless you increase somehow the air flow). Pay attention because going too rich will provoke excess fuel unburnt washing out oil film from cylinder walls and induce premature engine wearing (reduced compression).

2.- Increasing fuel line pressure not only allows more injector flow: it provides better fuel atomisation, wich improves idling and get rid of up to 4.000 RPM jerkiness, due to intake manifold low velocity air flow, on the stock engine. This is what I have also observed on my bike: better driveability. Considering people spend 500€ on "mithic expensive" piggyback ECU plus Dyno runs just to try to get rid of "notorius" driveability issues on this bike, you should agree that a 3,5 BAR 42€ FPR is a pretty good approach... Why won't you recommend this mod?

I disconnected the battery for a while to reset ECU and let it "learn" again closed loop operation with the new FPR and increased airflow / exhaust mods.

3.- An ECU SHOULD adjust air density (barometric correction) and intake manifold air temperature. Stock ECU is designed to cope with an enormous amount of different conditions as high altitude, extreme air temperatures, poor quality fuel, cooling malfunction (thousands of hours on factory bench dynos)... If you have to adjust the tune of your piggyback ECU every time weather changes may be you are doing something wrong, or maybe that ECU is just crap... This is why whenever possible, I prefer STICK to STOCK ECU.

Given the amount of views this topic generated, I will provide more data on MY setup, but not soon.

Regards,

 

Hey JZ, do you have an injector pulser? I'm curious if someone can actually show us the difference in spray pattern, if any, and on a stock injector, when it is changed to 50.7 versus 43.5 psi rail pressure.

Also... I may be speaking out of turn, but I thought the Bosch Engine Management systems were capable of adapting even open loop variables, after approx. 10-20 full trips, as far back as Euro3. Am I wrong about this?
[perhaps you see where I am going]

Not trying to make matters worse, guys... but even you, ALF, are saying you have not confirmed any of your claims with wideband data.
And for the record, an O2 sensor (not a wideband A/F sensor) only reads between 13.8 and 15.2; there is no more range to that type of system.
So a pre-wideband gasoline engine sensor can't even get you feedback to the point where you can say "Hey! I burned all the oxygen outta the intake charge!"
[oh crap, I'm going off on a tangent again...]

Not that I have any intention of changing my FPR, just to change the supposed rate I temporarily return-filter my fuel...(see attached pic)
but is anybody up to also 'showing' us the difference in the stock injector spray pattern?
[ok, I'm back to normal now]

Thanks guys. Or depending, perhaps I should only offer apologies.
Eh...

 

Hey JZ, do you have an injector pulser? I'm curious if someone can actually show us the difference in spray pattern, if any, and on a stock injector, when it is changed to 50.7 versus 43.5 psi rail pressure.

Also... I may be speaking out of turn, but I thought the Bosch Engine Management systems were capable of adapting even open loop variables, after approx. 10-20 full trips, as far back as Euro3. Am I wrong about this?
[perhaps you see where I am going]

Not trying to make matters worse, guys... but even you, ALF, are saying you have not confirmed any of your claims with wideband data.
And for the record, an O2 sensor (not a wideband A/F sensor) only reads between 13.8 and 15.2; there is no more range to that type of system.
So a pre-wideband gasoline engine sensor can't even get you feedback to the point where you can say "Hey! I burned all the oxygen outta the intake charge!"
[oh crap, I'm going off on a tangent again...]

Not that I have any intention of changing my FPR, just to change the supposed rate I temporarily return-filter my fuel...(see attached pic)
but is anybody up to also 'showing' us the difference in the stock injector spray pattern?
[ok, I'm back to normal now]

Thanks guys. Or depending, perhaps I should only offer apologies.
Eh...

View attachment 52970

Spray pattern is more related to the number of holes and how they are grouped on the injector nozzle. Clogged or dirt injectors can have their spray pattern altered. But in a clean injector, increasing the fuel line pressure won't change the spray pattern, it just will provide more flow and better fuel atomisation.

For a given injector flow, you can have a unique bigger hole, or 4 thinner holes, or 6 even more thinner holes and so on... The higher amount of holes the easier to get them clogged by poor gas quality and lack of fuel filter maintenance. KTM opted for a 4 hole injector wich is a sweet spot between a good spray pattern and not too prone to clogging injector.

In a clean injector, flow test results won't difere too much from math calculations... Testing is always good, but for example you don't need to test gravity each time something (or someone 🤣) falls. This is why we have science: good predictions (9.8m/s^2, on planet earth, wich is not flat 🌍...). Good predictions are always budget 🤣🤣🤣.

I've been unable to find the data sheet of this injector, so some testing with a previously cleaned stock injector @ 3.0 BAR (43.5PSI ) one minute 80% duty cycle would be nice. But let's make some good predictions:

New flow rate= ((original flow rate) x the square root of ((new pressure)/original pressure)).

To feed a naturally aspirated 44hp stock engine with a single injector considering 80% duty cycle, you will need injector flow of 290cc/min @ 3.0 BAR (27.5 lb/hr @ 43.5 PSI).

At 3.2 BAR (46.41PSI) the same injector will flow 300 cc/min (28 lb/hr). 3.5% flow increase.

At 3.5 BAR (56.76 PSI) the same injector will flow 313 cc/min (30 lb/hr). 8% flow increase.

At 4.0 BAR (58 PSI) the same injector will flow 335 cc/min (32 lb/hr). 15.5% flow increase.

For a 50hp target power (after "customization") engine, injector should flow 328cc/min (31 lb/hr).

To determine AFR's I absolutely agree the best way is a wideband lambda. Narrowband lambda (4 wires) only can detect severe fueling conditions when constantly detect rich or lean within it's range: they only measure a very narrow window of Air to fuel mixtures – around 0.99 to 1.01 lambda or 14.6 to 14.8:1 AFR (for hexaoctane: pure gasoline). So narrowband only tells you if engine is on the rich side or in the lean side... But it doesn't tells you how much...

Beware of "self learning" piggyback ECU's that use stock narrow band data inputs.
Regards,

 

Hi everyone!

This is my full recipe for real engine performance with contained costs and an eye on minimize knocking issues...

You will need all this material and do the installation following this order:

1.- Fuel Pressure Regulator: 3.5 Bar 42€
3,5 BAR KTM 390 Duke Bajaj 17- Regulador de Presión de Combustible 90207088000 | eBay

Stock FPR is rated @ 3.0 BAR. This 3.5 BAR will improve idle because of better fuel atomisation and enrich the open loop side of the throttle AFR to compensate more airbox flow and exhaust flow. No need for piggyback ECU, remap, bigger injector and all that messy expensive crappy stuff. Let stock ECU do the job.

Increasing air flow without compensating with more fuel lead t lean moistures, engine knocking and as consequence, reduced engine lifespan. More on this topic: fuel injector flow rate

You will need to disassemble the gas tank and extract the fuel pump assembly to install the new FPR... When finished all the upgrades, don't forget disconnecting the battery, for a couple of hours to reset ECU. Reconnect and run the bike a while in every RPM range (500 RPM steps) to let the ECU learn closed loop with the new FPR, decat pipe and airbox lid.

Where is the fuel pressure regulator located? I have my tank and fuel pump disassembled and am having trouble finding it.

2.- Iridium sparkplug: LKAR9BI9 - NGK 17,54€

Disculpa la interrupción...

With the fuel tank removed you will have easy access to the spark plug. Iridium spark plug allows bigger initial flame kernel and faster flame propagation. Also it can last for 50.000km or more, so less frequent need to service it.

3.- Decat pipe: Arrow 310€

COLLECTEUR RACING ARROW HUSQVARNA SVARTPILEN / VITPILEN 401 2020 | eBay

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www.ebay.fr

For the 2020 model, decat pipe is the full header pipe so it's more expensive, but 2019 and previous models can decat for 90€...

4.- Exhaust Wrap: 8,44€

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Before installing the Decat pipe you absolutely must wrap the exhaust header (and Decat pipe). Start wrapping from the tail side and end on the header side, to keep aerodinamic pattern and make it tough.
View attachment 52953
In 2019 and previous versions, the exhaust runs aside the TBI and air intake manifold. This caused heat soak and lack of performance due to air intake increased temperature. Hot air in the intake manifold induces engine knocking.

2020 models should also wrap because it helps keeping the combustion gases hotter and this improves flow velocity. So wrap all that crap...

5.- Air box lid: DNA P-KT3N20-S2 56€

KTM Adventure Series (20-23) DNA Air Box Cover Stage 2 P-KT3N20-S2

The DNA Stage 2 Kit, can be either a DNA filter or a DNA cover that is designed to replace a part of the air box, seriously increasing air flow to the engine. With the proper fuel recalibration the results are always very impressive.

www.e-dnafilters.es

This is the best air box lid. It increases air flow to the engine and make the engine sound as a BBB (big bad boy). So don't save money on this. Keep the stock paper air filter because engine's max RPM will remain the same as stock (no restriction on filter element).

6.- Mo Cool Motul: 11,50€

MOTUL mocool 0,5L : Amazon.es: Coche y moto

MOTUL mocool 0,5L : Amazon.es: Coche y moto

www.amazon.es

The more power, the more need to heat dissipation... KTM 390 and our 401's are famous for overheating and continuous fan operation. So ad Mo Cool to the cooling fluid. If necessary, drain some coolant to make room for this additive. Cooling system galore can lead to engine knocking.

7.- Militec1: 17€

5,98€/100ml MILITEC-1 Vollsynthetischer Ölzusatz Motorölzusatz Öladditiv Metallv | eBay

Entdecken Sie 5,98€/100ml MILITEC-1 Vollsynthetischer Ölzusatz Motorölzusatz Öladditiv Metallv in der großen Auswahl bei eBay. Kostenlose Lieferung für viele Artikel!

www.ebay.de

Metal conditioner, the best drag reductor in the world. It doesn't change original oil density, no sludge or metal deposits, no problems with bike's wet clutch... The engine will run smooth (less vibration), cooler, with less wearing. Also the less drag between engine moving parts the more power to the rear wheel. 2020 model quickshifter ("easy shift") runs espectacular with Miltec1 in the carter.

8.- 43Teeth rear sprocket: 60€

ZF ZFD-890-43-BLK | eBay

Entdecken Sie ZF ZFD-890-43-BLK in der großen Auswahl bei eBay. Kostenlose Lieferung für viele Artikel!

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We're increasing engine performance, so we're applying more torque to the rear wheel. This bike has no slip control so this rear sprocket will slightly reduce by 5% rear wheel applied torque when getting out the curves and also improves by a 5% bike's top speed. No need to modify chain length (number of Links) with this sprocket. Front sprocket remains stock (15 teeth).

Also this rear sprocket is aluminum core and stainless crown so lightweight and durable...

Use this sprocket calculator to determine the impact on bike's behavior with different sprocket ratios:

Sprocket Calculator - The easy motorcycle sprocket and chain calculator

9.- High octane fuel: this engine has high compression ratio: 12,5:1 and runs on the lean side AFR (Euro4). To avoid engine knocking (pinging) use high octane gasoline. Also from time to time fill it up with Shell V-Power NITRO to clean carbon build up in combustion chamber, valve heads and spark plug. Carbon spots induce knocking.

Stock mid muffler, stock tail muffler, stock Db killer, no money spent in sound. Sound doesn't make power. How many thousands of neighbours in a big city can be disturbed by just only one slip on idiot???🧐 If engine max RPM is not increased, hardly the stock muffler will be restrictive. Power= RPM * Torque. Yes, increasing engine's max RPM is good for power but it also affect engine's lifespan and that's not budget...

This is all: 500€ for 2020 models and 300€ for 2019 and previous models.

Mattighoffen engineers made a superb engine respecting Euro4 emissions. I respect burning fuel in the chamber to make power with efficiency instead of burning up fuel @ the cat to produce heat...

Those of you that say "if you want more power buy a bigger bike" are right. Spending thousands of € in a small engine performance increase is not worth. But you are also snob 🤣 and lack of technical knowledge. Real improvement can be done on this engine without spending too much.

The key for a reliable mod is always keep an eye on engine knocking wich is one of the most destructive events that can occur in an engine.

 

Can anyone confirm that the OEM pressure restrictor does in fact regulate the fuel pump pressure of 6 bar down to 3.0 bar or are our 390 engines equipped with a 3.5 bar regulator valve?

 

Just to let all of you know I still working on it: I'm gonna provide some updates.

NEW STYLE (2020 & up Husqvarna and 2021 & up KTM) FUEL PRESSURE REGULATOR ARE ADJUSTABLE FROM FACTORY. Guess why?😁

Note the new FPR at left side on images: smaller size and allen screw for adjustment. Still have to do some bench tests to determine the range of pressure adjustment.

This FPR is the same for 125 and 401 2020 & up Husky's.

Still preparing video and Dyno session...

Regards.

 

Interesting and good news/find Alf.
Also, I enjoy your explanation except for the unnecessary political part in the last few sentences.
Your opinion is just that.
An opinion is like an arsehole, everyone has one so perhaps you can keep that to yourself and not degrade your technical splendid efforts by this.

Just to let all of you know I still working on it: I'm gonna provide some updates.

NEW STYLE (2020 & up Husqvarna and 2021 & up KTM) FUEL PRESSURE REGULATOR ARE ADJUSTABLE FROM FACTORY. Guess why?😁

Note the new FPR at left side on images: smaller size and allen screw for adjustment. Still have to do some bench tests to determine the range of pressure adjustment.

This FPR is the same for 125 and 401 2020 & up Husky's.

Still preparing video and Dyno session...

Regards.

 

Unless the fuel pressure regulator can be adjusted by the ECU then I think you may be reading too much into it. KTM may be fitting an adjustable regulator but they don’t offer tuning options in that sense because it would then fail the emissions regulations. If it happens to be adjustable because that is what the supplier is providing then KTM are in the clear.

 

If new FPR's are ADJUSTABLE is because KTM wants to... The same FPR can be produced at lower costs without being adjustable. KTM is fabricating in India because they don't care of costs???

Yearly emissions control in EU stand only for opacity in exhaust gases (particles). The problem is new model homologation: factory set the vehicle to comply with regulations but as a result the vehicle sucks: driveability issues, lean moistures (overheating, knocking and reliability issues). Or engine displacement have to be increased just to keep the same performance as the previous Euro4 version.

The ECU controls injector pulse width. In closed loop uses O2 lambda narrow band readings to correct air fuel ratio. In open loop the ECU only uses injection map as target, without lambda correction: the injector pulse width is the same @ 3.0BAR, 3.5 BAR or @ 4.0 BAR, but the injector flow isn't and the ECU is dumb to that fact. This way additional air flow (decat, air box lid...) can be compensated with more fuel injection. FPR tuning stands for wide open throttle. This has been explained several times in this topic, Mirius Pirricus. 😘

With the adjustable FPR, dealers can now easily adjust the bike (let's say a sporky but reliable 125cc bike) in order to have any chance to sold it after a costumer test drive... Without electronics or remapping, without diesel gate like issues. And now, with the knowledge on this topic, owners also can do it... Is not perfect, but is simple and it works.

Euro7 emissions standard will have the only purpose to make ICE vehicles more expensive than umbilical ones. Climate is changing as always but it hasn't anthropogenic causes. China is killing us with viruses but not with CO2 emissions. So keep calm and enjoy your bike.

 

I’m not a super moderator but I’m not interested either. I’m very conspiracy oriented and I have big company experience so I understand at first hand how it works. But in this context? No. This is a bike forum, so not appropriate.

The issue here is that KTM will not approve something that risks their emissions approval. No KTM dealer will be approved to make such modifications - any dealer that is found making adjustments to the pressure regulator will be immediately not a dealer. KTM are EU based. They have zero ability to include the ability to make modifications. Japanese manufacturers yes - clear evidence of playing games. EU manufacturers cannot afford that risk. You can see this clearly with Akrapovič and also with Triumph.

 

I’m not a super moderator but I’m not interested either. I’m very conspiracy oriented and I have big company experience so I understand at first hand how it works. But in this context? No. This is a bike forum, so not appropriate.

The issue here is that KTM will not approve something that risks their emissions approval. No KTM dealer will be approved to make such modifications - any dealer that is found making adjustments to the pressure regulator will be immediately not a dealer. KTM are EU based. They have zero ability to include the ability to make modifications. Japanese manufacturers yes - clear evidence of playing games. EU manufacturers cannot afford that risk. You can see this clearly with Akrapovič and also with Triumph.

There's a huge gap between what dealers are allowed to do and what they really do to keep sales up. But as big company guy, you should already know this. Dealers cover liability issues having the written acknowledgment signed by the costumer: only circuit use, not street legal, bla, bla, bla... Precisely Husqvarna dealers with the Enduro and Cross line of bikes, are frequently unlocking performance features on it's bikes... Off road use only.... Ya...

You are not an European Union citizen anymore since brexit, Mirius Pirricus 😘. The only responsability of vehicle manufacturers in European Union is that new model launched at the market comply with emissions regulations, and they do that. What you do with your vehicle is not their fault.

I'm not a big company guy 🤣, but I can imagine several reasons to switch to an adjustable FPR: economies of scale (you can use the same part in almost every model you launch), you can configure the bike to different market regulations, different fuel octane rate, different climates (in an easy way without dealing with dozens of ECU maps that have to be also upgraded from time to time), you can enhance the performance in the several racing categories, and why not: you can left an open door to customization and dealer aftermarket product sales (in free countries costumers like different things and have different points of view, and so on...

This is why another important goal of the future Euro7 is making very hard that engine mods pass inadvertently on yearly inspections...

First time I was being ironic, after red censorship I was being sharp. Emissions and climate politics (nobody talks about climate science) are pertinent more than ever in a bike forum. However I have done numerous contributions in a form of technical knowledge to this bike forum, so I don't give a d**n about what you think is or not appropriate.

This is bike forum but I'm not only a bike guy. You will have to live with that...

 

A thought; if you manage to increase the flow/volume of the injector or mount a larger capacity injector, would the ECU not cut the opening times in order to comply with its lambda sonde readings and bring it back down?
I guess all work fine in the higher regions where, apparently, our OEM injector can't cope.

 

Hi Super!

Yes and no. Your bike is like Dr. Jekyll and Mr. Hyde. 😉

What you state is true when your bike ECU uses O2 sensor lambda correction. This operation mode is called "closed loop" (Dr. Jekyll side of the story). In this mode, if you increase fueling by higher pressure rated regulator or by a larger flow inyector, the ECU will try to shorten the pulses sent to the injector to try to match the specified air/fuel ratio defined in ECU fuel maps.

Closed loop operation only enables frow low to medium RPM and steady or almost constant RPM in this range.

But your bike is also Mr. Hyde: The lambda correction system doesn't have enough time to make corrections during heavy acceleration and higher RPM. In this conditions the ECU switches to Open Loop mode and uses pulse length as predefined in Injection maps, without using lambda correction.

This is why when you improve the air flow (air box mods & exhaust mods) and also increase fueling (higher pressure regulator or higher flow injector), the engine behavior in low and medium loads and RPM, remains "civilized", but when the ECU switches to Open Loop, additional power is made avoiding lean moistures. This is why I always say that "FPR" tuning is for wide open throttle.

FPR tuning is not as perfect as Dyno remap but is still a power build and cost effective way to compensate for more air flow mods and to avoid lean moistures.

The only thing I absolutely respect is people that question and try to learn, and I will always try to help with my limited knowledge and teaching hability.

Regards.

 

Great so in the closed-loop it does not really matter as the ECU will regulate according to what lambda says, but at higher revs and open-loop it now provides the bike with the fuel it needs in able to make the HP's it was designed for, right?

 

Well, is a little more subtle... When you modify your bike with more air flow and more fuel flow, in closed loop the ECU have as target lean moistures to reduce emissions and to save fuel. But anyway more air and more fuel is being delivered: so you can expect better driveability and get rid on 2000 to 4000 RPM jerkyness...

If you set the right FPR pressure, when open loop " kicks in" you can expect power and a silly smile. Be cautious for the first and wear a helmet for the second 🤣...

In case of FPR tuning you can expect also better idling. FPR increase is better than bigger injector option when possible.

 

Well ladies & guys: just pay attention because these are pictures that until now were unable to be found with such detail on Google...

First of all we have to distinguish between old style fuel pump and new style ones.

This is oval shaped old style one:

These use standard FPR rated at a fixed pressure. You need to replace the FPR by other one rated at higher pressure to adjust air intake and exhaust mods. The good news: is very easy just remove the fuel pump and free the iron wire clamp and make the FPR replacement. The bad news: you have to purchase the new higher pressure rated FPR.

And this is the new style fuel pump: it occupy less volume inside the tank so more fuel can be carried with a smaller tank. It also features far better sealing gasket and torque plate.

The good news: it features adjustable stock FPR, no need to buy nothing. The bad news: the procedure is slightly more tricky:
Free the plastic enclosure of the fuel pump and retract the pump to make room to pull out the FPR. No need to remove the fuel filter bag.

Insert a thin screw driver 5mm into the FPR hole and make some sort of lever to gently pull out the FPR.

Use a CD pen to make a mark between FPR housing and the screw to see how much additional compression in form or screw turns you put on the inner spring.

Adjust clockwise with an allen key until you reach the desired opening pressure.

This is a safe and budget setup to a FPR. Air density is lower than gas density so to achieve 3,5 BAR opening pressure with gasoline, you have to adjust the screw to open the FPR with 3,2 BAR air. I set mine to 3,8 BAR on gasoline.

Make sure FPR o-ring is in good shape. Reverse mount everything.

For safety reasons, when dealing with fueling systems always disconnect the battery. This is also needed to reset the ECU, and force it to learn again closed loop operation with the new (or adjusted) FPR, air box lid, decat pipe...

The inmediate seat of the pants experience for this setup is better and consistent idling, getting rid of jerkyness from 2.000 to 4.000 RPM (better driveability), faster acceleration transitions and power increase noticeable from 6.000 RPM and up.

I need to get this Dyno proven, but not for me: just for all of you. 😉

Until then, enjoy your ride...

 

Well ladies & guys: just pay attention because these are pictures that until now were unable to be found with such detail on Google...

First of all we have to distinguish between old style fuel pump and new style ones.

This is oval shaped old style one:
View attachment 53532
These use standard FPR rated at a fixed pressure. You need to replace the FPR by other one rated at higher pressure to adjust air intake and exhaust mods. The good news: is very easy just remove the fuel pump and free the iron wire clamp and make the FPR replacement. The bad news: you have to purchase the new higher pressure rated FPR.

View attachment 53531
And this is the new style fuel pump: it occupy less volume inside the tank so more fuel can be carried with a smaller tank. It also features far better sealing gasket and torque plate.
View attachment 53534
View attachment 53533
The good news: it features adjustable stock FPR, no need to buy nothing. The bad news: the procedure is slightly more tricky:
Free the plastic enclosure of the fuel pump and retract the pump to make room to pull out the FPR. No need to remove the fuel filter bag.
View attachment 53535
Insert a thin screw driver 5mm into the FPR hole and make some sort of lever to gently pull out the FPR.
View attachment 53536
Use a CD pen to make a mark between FPR housing and the screw to see how much additional compression in form or screw turns you put on the inner spring.
View attachment 53537
Adjust clockwise with an allen key until you reach the desired opening pressure.
View attachment 53538
This is a safe and budget setup to a FPR. Air density is lower than gas density so to achieve 3,5 BAR opening pressure with gasoline, you have to adjust the screw to open the FPR with 3,2 BAR air. I set mine to 3,8 BAR on gasoline.

Make sure FPR o-ring is in good shape. Reverse mount everything.

For safety reasons, when dealing with fueling systems always disconnect the battery. This is also needed to reset the ECU, and force it to learn again closed loop operation with the new (or adjusted) FPR, air box lid, decat pipe...

The inmediate seat of the pants experience for this setup is better and consistent idling, getting rid of jerkyness from 2.000 to 4.000 RPM (better driveability), faster acceleration transitions and power increase noticeable from 6.000 RPM and up.

I need to get this Dyno proven, but not for me: just for all of you. 😉

Until then, enjoy your ride...

Thank you Alf for sharing your experience! Mauro

 

Been browsing these forums for a while thought I would add up what I have found. Don't mean to hijack the thread, and apologies for straying off topic but I started responding and got too carried away typing.

I have been datalogging this bike with Hptuners MPVI2 via OBD2 adapter. This records internally (with the pro features option)
It does not officially have support for this ECU, but it grabs quite a few PID's through standard OBD2 canbus.

I have also installed an AEM UEGO wideband O2 on a cat eliminator. This particular model also will send its reading over OBD2 via an insert adapter you can see below. That way the data stream is entirely synced up and you can see more precisely what's going on. The AEM wideband I am using is the fastest response time of any wideband you can get with the exception of 1 or 2 others.

I am also running a open top airbox of my own design and a powertronic ecu.

This is one way to properly datalog this bike....but even then this is 1/2 the data I really need to tune this properly. Any more would require some canbus sniffing and likely carrying around a laptop.

Here is the PID's I am pulling. The 1 highlighted in red is from the AEM UEGO Wideband which merges into the OBD datastream.

Basically I can tell you these injectors do have enough flow to get all the way to .8 lambda at 8500 RPM at full load and even richer.
There is no need to ever throw larger injectors in this bike, unless you are significantly increasing airflow way beyond an airbox lid and exhaust.
The problem is in the stock mapping.

Contrary to popular belief, this bike enters open loop all the time.
Closed loop operation happens at part throttle and cruising. But open loop is entered as low as 1500 rpm.
This is in an acceleration state. You can see below. (this was a a blip of the throttle at the lights, as you can see the only changes are map pressure and the narrowbands o2 reading. (The lack of MAF is just a design choice. Ford uses MAF, Dodge uses MAP, GM uses both. It does the same job as a MAF. People seem to think every vehicle requires a MAF but you can go either way, and there are +and - to both.)

At the open loop portion it enters the matrix of its multiple fueling maps, there are at least 7. Some are for component protection (dumping fuel to protect the catalytic converter and O2 sensor) and some are combustion and efficiency tables. These get referenced and out comes your injector pulse.
I haven't fully discovered the logic as to when it enters into acceleration mode, but suffice to say whenever you punch it...you are there.....not just 65% throttle and 8500 RPM as some have stated (powertronic themselves i believe) it is usually accompanied by a fast twist of the throttle.

I can fully back this claim up as well with hard data. In my logs....literally every time I accelerate hard it is in open loop. The other clue is the STFT or short term fuel trims, which are responding to the stock narrowband and completely disable and show zero during all open loop operation, these completely coincide with the open loop states.

What I have found is stock, with no piggyback computer and cat eliminated and open top airbox...the stock ECU and injectors will hit as rich as .8 lambda at 8500 rpm full load. (Load is an OBD specified and inferred parameter but the MAP sensor also shows when you are there).

Where it runs into a little trouble is 5500-7000 RPM where with this combo it can effectively lean out to 1.15 Lambda and above....

Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods.

This is effectively where the piggybacks come in. I am dialing in my Powertronic tables now incrementally.

While increasing the fuel pressure should help open loop operation, it can in a lot of vehicles be negated by the LTFT (long term fuel trim)
This can be reset by disconnecting the battery, however the ECU learns the LTFT over time from the info it receives by watching the STFT (STFT is near instantaneous and isnt kept in memory after turned off...you can see it in my logs)
LTFT's job is generally to adjust to changing conditions (wear, lower compression, dirty plugs ect) and is sometimes referenced and multiplied by the open loop tables. I have no reason to believe this is indeed the case for the Duke ECU, but there are some other reasons it may be better not to play with pressure.

A lot of data internal logic that would usually require sensors is inferred by this ECU....engine knock protection being the biggest one. The ECU infers things like octane and combustion limits from the combinations of sensors it has, and the change in fuel pressure could screw that up. There are at least 13 different ignition tables in this ECU....most of them are divided into high octane and low octane categories, which it has to infer from available sensors.

I'm not saying not to do it....just given any other option (like a piggyback) I likely wouldn't touch pressure unless I know there is a table for pressure and a pressure sensor as these modern ECU's are getting pretty advanced logic, and you don't know how a seemingly unrelated value will cascade. Some newer Dodges actually run neural networks instead of certain tables....suffice to say a lot going on in there.

Just FYI, scaling injectors properly is probably the single hardest part of any tuning job as there is way more that just pressure. There usually will be entire tables referencing injector response (not sure in the Dukes case) and almost always you need data supplied by the injector manufacturers unless you literally want to spend $15k on dyno time dialing in the injectors.
The pic below shows a Ford V10 Copperhead ECU injector controls. Each button shown leads to a separate table.

 

Been browsing these forums for a while thought I would add up what I have found. Don't mean to hijack the thread, and apologies for straying off topic but I started responding and got too carried away typing.

I have been datalogging this bike with Hptuners MPVI2 via OBD2 adapter. This records internally (with the pro features option)
It does not officially have support for this ECU, but it grabs quite a few PID's through standard OBD2 canbus.

I have also installed an AEM UEGO wideband O2 on a cat eliminator. This particular model also will send its reading over OBD2 via an insert adapter you can see below. That way the data stream is entirely synced up and you can see more precisely what's going on. The AEM wideband I am using is the fastest response time of any wideband you can get with the exception of 1 or 2 others.
View attachment 53579
View attachment 53583

I am also running a open top airbox of my own design and a powertronic ecu.
View attachment 53584

This is one way to properly datalog this bike....but even then this is 1/2 the data I really need to tune this properly. Any more would require some canbus sniffing and likely carrying around a laptop.

Here is the PID's I am pulling. The 1 highlighted in red is from the AEM UEGO Wideband which merges into the OBD datastream.
View attachment 53580

Basically I can tell you these injectors do have enough flow to get all the way to .8 lambda at 8500 RPM at full load and even richer.
There is no need to ever throw larger injectors in this bike, unless you are significantly increasing airflow way beyond an airbox lid and exhaust.
The problem is in the stock mapping.

Contrary to popular belief, this bike enters open loop all the time.
Closed loop operation happens at part throttle and cruising. But open loop is entered as low as 1500 rpm.
This is in an acceleration state. You can see below. (this was a a blip of the throttle at the lights, as you can see the only changes are map pressure and the narrowbands o2 reading. (The lack of MAF is just a design choice. Ford uses MAF, Dodge uses MAP, GM uses both. It does the same job as a MAF. People seem to think every vehicle requires a MAF but you can go either way, and there are +and - to both.)
View attachment 53581

At the open loop portion it enters the matrix of its multiple fueling maps, there are at least 7. Some are for component protection (dumping fuel to protect the catalytic converter and O2 sensor) and some are combustion and efficiency tables. These get referenced and out comes your injector pulse.
I haven't fully discovered the logic as to when it enters into acceleration mode, but suffice to say whenever you punch it...you are there.....not just 65% throttle and 8500 RPM as some have stated (powertronic themselves i believe) it is usually accompanied by a fast twist of the throttle.

I can fully back this claim up as well with hard data. In my logs....literally every time I accelerate hard it is in open loop. The other clue is the STFT or short term fuel trims, which are responding to the stock narrowband and completely disable and show zero during all open loop operation, these completely coincide with the open loop states.

What I have found is stock, with no piggyback computer and cat eliminated and open top airbox...the stock ECU and injectors will hit as rich as .8 lambda at 8500 rpm full load. (Load is an OBD specified and inferred parameter but the MAP sensor also shows when you are there).

Where it runs into a little trouble is 5500-7000 RPM where with this combo it can effectively lean out to 1.15 Lambda and above....

Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods.

This is effectively where the piggybacks come in. I am dialing in my Powertronic tables now incrementally.

While increasing the fuel pressure should help open loop operation, it can in a lot of vehicles be negated by the LTFT (long term fuel trim)
This can be reset by disconnecting the battery, however the ECU learns the LTFT over time from the info it receives by watching the STFT (STFT is near instantaneous and isnt kept in memory after turned off...you can see it in my logs)
LTFT's job is generally to adjust to changing conditions (wear, lower compression, dirty plugs ect) and is sometimes referenced and multiplied by the open loop tables. I have no reason to believe this is indeed the case for the Duke ECU, but there are some other reasons it may be better not to play with pressure.

A lot of data internal logic that would usually require sensors is inferred by this ECU....engine knock protection being the biggest one. The ECU infers things like octane and combustion limits from the combinations of sensors it has, and the change in fuel pressure could screw that up. There are at least 13 different ignition tables in this ECU....most of them are divided into high octane and low octane categories, which it has to infer from available sensors.

I'm not saying not to do it....just given any other option (like a piggyback) I likely wouldn't touch pressure unless I know there is a table for pressure and a pressure sensor as these modern ECU's are getting pretty advanced logic, and you don't know how a seemingly unrelated value will cascade. Some newer Dodges actually run neural networks instead of certain tables....suffice to say a lot going on in there.

Just FYI, scaling injectors properly is probably the single hardest part of any tuning job as there is way more that just pressure. There usually will be entire tables referencing injector response (not sure in the Dukes case) and almost always you need data supplied by the injector manufacturers unless you literally want to spend $15k on dyno time dialing in the injectors.
The pic below shows a Ford V10 Copperhead ECU injector controls. Each button shown leads to a separate table.
View attachment 53582

Yes, your post is some kind off topic. Because this was about a BUDGET way to increase performance in a small displacement engine. But unless we got again "Super's 😘 Red Censorship" 🤣, this is a free topic. So let's understand what you are talking about💸 :

Hptuners MPVI2 pro: 477.75€
VCM scanner suite: 20€
AEM UEGO wideband O2 controller: 293.00€
Powertronic piggyback ECU: 396,21€
Cat eliminator: 90€ + bung + welding or 300€ for the full header in new models + bung + welding
Air box lid: 56€
Dyno runs?

So you are talking about a let's say 1.500€💸 or more customization. 21% cost increase over the MSRP price of a brand new KTM 390: 6.049€.

Unless you are a professional tuner (if you are selling something you should advise people in this forum), this mod is out of reach for the average rider. Don't forget KTM is a global firm that operates in markets where the materials you are proposing are simply unavailable or have an absurd cost compared to the average wage. For example: most asian and south America countries. So FAHGETTABOUDIT.

KTM duke 390 doesn't have OEM onboard knock sensor. Ignition advance maps and fueling maps have been determined by thousands of hours at Mattighoffen dynos bench tests using lab piezoelectric mics designed to "listen" determined frequency: (Knock Frequency = 900,000/(π×0.5 ×cylinder bore diameter )).
Also the KTM duke390 has not fuel density sensor (flex fuel sensor able to detect octane changes in fuel and ethanol % present in fuel) only a fist of Brazilian market (Yamaha YS250 Fazer, Factor 125i, Honda CG160 Flex... all of them low displacement single cilinder bikes) bikes.

Trying to outperform Factory ECU settings with a piggyback ECU and a laptop??? FAHGETTABOUDIT.

Yes open loop "kicks in" in accel transient and wot . This is I always stated constantly and consistently in this topic (and others). The lambda correction system doesn't have enough time to modify injector pulse width during transitions and high RPM.

You state that with decat pipe and open air box the stock ECU reaches 0.8 lambda at 8.500 RPM full load. This is less than 12 AFR, quite on the rich side. But you also state "Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods." If the first statement is true, there's no need for FPR tuning or piggyback ECU to avoid lean conditions. What everyone have observed in this bike is that with flow improvements there's need to increase fueling...

Increasing fuel rail pressure improves fuel atomization, and this helps with idling and low rev operation driveability. LTFT in a single cylinder engine is mainly for closed loop operation. LTFT is mainly used to compensate between two cylinder banks (V2, V4, V6, V8... with dual lambda settings), and to compensate for fuel, ignition, and engine problems.

In open loop, the ECU is dumb to the presence of increased fuel rail pressure. No issues. Is a simple yet effective way to get rid of lean moistures after air flow and exhaust upgrades, is not perfect as also piggyback isn't. FPR tuning has more effect on closed loop than piggyback (piggyback ECU doesn't control closed loop), so is more indicated to solve driveability issues.

To properly tune a piggyback ECU you need also Dyno runs.

I'm not saying not to do it, 🤣 but I won't use of a piggyback ECU just to compensate for slight changes in air flow and exhaust flow or just to try to get rid of driveability issues. Just for extreme modifications where the stock ECU has no more room for corrections and street driveability isn't an issue. I understand those who spend zillions on piggyback ECU's and those who sell them, need backup for that kind of decisions ...

 

Yes, extremely off topic..sorry
I would delete this thread and move it if I could so as not to take away from the great info you have posted about the fuel pressure mod, so I'll just leave this final reply.

Firstly as far as budget...ya way off.

I happened to have most of this lying around. (with the exception of powertronic and the decat pipe)
If you are paying for the VCM suite FYI you are getting scammed.

Best cheap method for some open loop protection - definitely fuel pressure mod.
For closed loop drivability.....some atomization increase....maybe.

"You state that with decat pipe and open air box the stock ECU reaches 0.8 lambda at 8.500 RPM full load. This is less than 12 AFR, quite on the rich side. But you also state "Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods." If the first statement is true, there's no need for FPR tuning or piggyback ECU to avoid lean conditions."

The first statement can still be true, but don't stop reading there.
.8 is a peak. It will generally hover around .92 with mods....so they were likely aiming for a little richer than that in the tables. As stated between 5000-7000 it is absolutely is running lean, and still under full load. Load being a maxed out MAP pressure. Lean under full load meaning engine damage. Higher up the RPM range the table seems to be ok, but the airflow mods are having their greatest impact between 5-7k rpm and running dangerously lean on stock ecu.


"KTM duke 390 doesn't have OEM onboard knock sensor. Ignition advance curves and fueling maps have been determined by thousands of hours at Mattighoffen dynos bench tests using lab piezoelectric mics designed to "listen" determined frequency: (Knock Frequency = 900,000/(π×0.5 ×cylinder bore diameter ))."

If you read what i wrote you will see I indicated the knock protection values are inferred. Meaning there is no knock sensor (all of which are piezoelectric mics) and the octane rating determines which advance table to use. As this bike will be knock limited (meaning max spark advance limited by engine knock before it can achieve optimum power) the inbuilt advance table itself is the knock protection.

"Also the KTM duke390 has not fuel density sensor (flex fuel sensor able to detect octane changes in fuel and ethanol % present in fuel) only a fist of Brazilian market (Yamaha YS250 Fazer, Factor 125i, Honda CG160 Flex... all of them low displacement single cilinder bikes) bikes."

Although it doesnt have a flex fuel sensor, the multiple fuel and spark octane tables in the ECU show it absolutely infers octane through available sensors (o2) and the difference from its expected interaction with the MAP table. Those inferred octane values determine which spark and fuel table the ECU references. As stated there are at least 13 separate spark advance tables (6 high octane, 6 low octane and a few extras)

"FPR tuning has more effect on closed loop than piggyback (piggyback ECU doesn't control closed loop), so is more indicated to solve driveability issues. "

Piggyback does try to control open loop, but FPR and piggyback will both be affected by STFT and LTFT in open loop. They both try to increase fuel, 1 by increased pressure....the other by overriding injector pulse width. They both will have their STFT learned by the LTFT and their effect will be negated back to Lambda. The STFT can be slow to react and you can have initial benefit with both systems while accelerating.

"LTFT is mainly used to compensate between two cilinder banks (V2, V4, V6, V8... with dual lambda settings), and to compensate for fuel, ignition, and engine problems. "

LTFT's are 100% in no way meant for dual bank balance. Each bank has its own STFT and LTFT reading and they have no relationship nor would they need to. They are exactly what they say, long term learned memory from short term fuel adjustments.
Whether or not LTFT affect open loop are dependent on ECU logic.


"To properly tune a piggyback ECU you need also Dyno runs. "

Not to tune AFR.
If I have a target AFR for optimum power you can easily aim for those targets datalog it cell by cell and update the cells in the piggyback, rinse and repeat. I don't think you could get a repeatable measurement on a dyno on the difference between 12 and 12.5 AFR.
Max power is gonna be influenced way more via ignition timing more than fuel. Since the ignition is knock limited, the timing part is easy....take it until just before it knocks and back off 2-3 degrees. Finding knock is a little trickier.

"Trying to outperform Factory settings with a piggyback ECU and a laptop??? FAHGETTABOUDIT."

Factory setting so good that everyone complains about low rpm drivability? Even in a factory tuned vehicle the fist step in tuning it is scaling and verifying the MAP or MAF, and where it rears its ugly head is low rpm drivability. Anyone can tune WOT. Others who have tuned the ECU's complain about the volumetric efficiency tables being off...and this is exactly what causes drivability issues. I agree this cant be totally solved with a piggyback (or fuel pressure mod) with both systems you are modifying fueling but both systems will be fighting STFT once acceleration is out of the way.

"I'm not saying not to do it, 🤣 but I won't use of a piggyback ECU just to compensate for slight changes in air flow and exhaust flow or just to try to get rid of driveability issues. Just for extreme modifications where the stock ECU has no more room for corrections and street driveability isn't an issue. I understand those who spend zillions on piggyback ECU's and those who sell them, need backup for that kind of decisions ..."

These slight changes in flow can push lambda up to 1.2 at 6000 rpm, as measured....
If your fuel pressure mod can handle a 20% increase in fuel then there is nothing to worry about....otherwise some massive injector pulse offset is needed as running lean on a 12.7:1 compression engine is a recipe for disaster.

 

As I told you this is a free topic and any point of view is welcome. No need to delete or move nothing.

Now I better understand your statement... So yes: there's need to enrich after flow mods. Nice info.

Octane rate is a measure that indicates the resistance to auto ignition of a fuel, or in other words resistance to knocking. 95 octane fuel is less resistant (prone to knocking) than 98 octane fuel. Pure ethanol is 120 octane (or more depending on the content % of water). Fuel Octane is determined by refinery. Higher octane fuels are indicated for high compression engines, so they can run more efficiently without Knocking issues. KTM recommend 95 octane fuel for this engine. So using 98 octane fuel as I recommend after a flow upgrade, provides additional safety margin against knocking.

Except for flex fuel vehicles, the only indirect (and cost effective) way for a ECU to know something is wrong with fuel's octane (or also lean AFR, or too advanced ignition, or cooling system malfunction, or intake hot air temperature, or chamber carbon deposit hot spots...) is knock sensor. Flex vehicles are more resistant to adulterated and low quality fuels. This Is why I stated several times in this topic that factory maps are conservative and able to cope with different and extreme conditions. Of course it comes at cost in form performance. Knock sensing system systems and their correction policy's aren't also perfect. The only perfect ECU is SAAB ION SENSING.

Tuning just for AFR doesn't grant max power nor efficiency. It only grants no lean or rich issues. To tune a vehicle you just need a Dyno (able to deal with partial loads to determine ignition advance maps). Beware of "self learning" piggyback ECU's that use stock narrow band inputs. If you don't have means for that, do FPR tuning. I don't mind STFT at closed loop.

Factory settings have to comply with emissions regulations and yes, they kind of suck. But the way factory comply with that is optimal. As a result stock engine run most of the time at lean side but they are designed with this in mind. If you read carefully my recipe I work to minimize knocking issues by all means available. FPR tuning can arrive to 20% enrichment on this bike. But my calculations lead me to estimate that a 15% increase (4 Bar FPR) @ injector duty cycle with my setup is more than enough to avoid knocking with the stock ECU.

 

As I told you this is a free topic and any point of view is welcome. No need to delete or move nothing.

Now I better understand your statement... So yes: there's need to enrich after flow mods. Nice info.

Octane rate is a measure that indicates the resistance to auto ignition of a fuel, or in other words resistance to knocking. 95 octane fuel is less resistant (prone to knocking) than 98 octane fuel. Pure ethanol is 120 octane (or more depending on the content % of water). Fuel Octane is determined by refinery. Higher octane fuels are indicated for high compression engines, so they can run more efficiently without Knocking issues. KTM recommend 95 octane fuel for this engine. So using 98 octane fuel as I recommend after a flow upgrade, provides additional safety margin against knocking.

Except for flex fuel vehicles, the only indirect (and cost effective) way for a ECU to know something is wrong with fuel's octane (or also lean AFR, or too advanced ignition, or cooling system malfunction, or intake hot air temperature, or chamber carbon deposit hot spots...) is knock sensor. Flex vehicles are more resistant to adulterated and low quality fuels. This Is why I stated several times in this topic that factory maps are conservative and able to cope with different and extreme conditions. Of course it comes at cost in form performance. Knock sensing system systems and their correction policy's aren't also perfect. The only perfect ECU is SAAB ION SENSING.

Tuning just for AFR doesn't grant max power nor efficiency. It only grants no lean or rich issues. To tune a vehicle you just need a Dyno (able to deal with partial loads to determine ignition advance maps). If you don't have means for that, do FPR tuning. I don't mind STFT at closed loop.

Factory settings have to comply with emissions regulations and yes, they kind of suck. But the way factory comply with that is optimal. As a result stock engine run most of the time at lean side but they are designed with this in mind. If you read carefully my recipe I work to minimize knocking issues by all means available. FPR tuning can arrive to 20% enrichment on this bike. But my calculations lead me to estimate that a 15% increase (4 Bar FPR) @ injector duty cycle with my setup is more than enough to avoid knocking with the stock ECU.

I agree with all of that 100% with a slight caveat on dyno tuning and AFR.
Most NA engines out there will have max power somewhere around lambda .85 +- .04 considering the engine.
On a typical 350 hp engine on a dyno, dropping lambda from 1.0 to 0.9 usually results in a difference of 1-3 ft/lb of torque gain.
All I am saying is that on a 43hp engine the toque increase would be almost undetectable and unrepeatable on the dyno between .87 and .82 lambda. So yes you could tune to find the sweet spot, but your better just erring on the rich side a tiny bit and calling it a day. Drastically more power comes out of timing.

The other thing usually accomplished on the dyno is finding MBT. This is an increase in timing until either knock occurs, or torque decreases. If knock occurs before torque decreases....the engine is knock limited. With our high compression engines this is guaranteed to be the case unless you were to use some high quality racing fuel.

Its a hard and inconvenient limit in the fact that there is missing torque you cannot access on regular fuel, but it makes tuning easy. Find knock and back off as many degrees as you are comfortable with and you are literally at the peak torque (you've allowed)
Not having a knock sensor likely means they significantly erred on the side of caution as far as the tables are concerned and there is some torque to be had, but it better be accompanied with some extra fuel.

"The only perfect ECU is SAAB ION SENSING"
You mean the system Harley Davidson uses
That has been around for a while in quite a few vehicles...mercedes does it with dual spark plugs, one as the ion sensor the other as the spark source and then alternating between them (i think in the older gen v12's.) It has big problems at low load and although it is pretty promising its not as revolutionary (currently) as it is usually described. Hence the low adoption. I like the idea, but knock sensors can be pretty good as long as the filtering is set properly.

The revolutionary part of ion sensing is calculating cylinder pressure. Right now that is done by the OEM with some pretty specialized equipment and expensive that can survive the combustion process in a test lab. Your goal through ignition advance is highest cylinder pressure without knock at around +20degrees TDC. (con rod/crank dependent). The ion sensing could potentially give you this data without a dyno and open up closed loop ignition tuning. To date no one has implemented this properly that I know of.

 

I will buy a piggyback ECU when it features Ion Sensing. Ion Sensing was developed by Linköping University at Sweden and Saab. Ville Vartiovaara is my hero: he did ion sensing for real time ignition tuning. Saab(Delphi) sold it to GM, and Harley Davidson. So further development become crap...

In a Harley it makes sense using Ion Sensing because backwards cilinder runs less refrigerated (more prone to knocking). So you have two cilinder running at different ignition timing and AFR.

Ion Sensing mirroring is like an onboard Dyno. Inicially It was used for knock sensing but later development made possible using it for MBT detection, on board, real time, cilinder to cilinder.

We have ended aiming a future with umbilical vehicles because ion sensing was not adopted by the whole industry.

And it used plasma jet discharge. So no problem with low load. Plasma jet is also big deal: you can achieve Maximum Brake Torque with conservative ignition timing. Faster flame propagation due to initial combustion kernel 300 times bigger than in a common spark plug.

Until then, with civilized flow improvements in a small displacement engine: I choose budget FPR tuning. As you said absolut precision defining ideal AFR in this kind of engine is not such a big deal...

 

And I would buy another piggyback if it had ion sensing
There is a bunch of DIY guys playing with it on home built ecu’s….very technical to calibrate from what I gather.

Ion Sense - rusefi.com

 

Interesting!
I have designed and tested several prototypes of plasma jet ignition. Is the ideal complement for ion sensing: plasma jet discharge takes only 2 to 6 ms so it is very precise timing and the rest of the combustion time window can be used for ion sensing mirroring between spark plug electrodes...

Here's a couple of videos of early prototypes I made:

Nice stuff...

 

Hello Alf, grateful for your guide, I'm riding a 2021 Svartpilen, motor same as KTM 390, also paid/downloaded repair Manual; currently researching cure for lean and jerky fuelling on the Euro-5 2021 model. This spoils ride in urban traffic, on open road at high rpm bike is fine. Working through your numbers, appears that injection pressure is higher than the 3.0 Bar you quote; on the later bike already 3.2...3.7 Bar, possibly to improve emissions and fuel atomisation? Intend stripping the tank and pump, what extra pressure do you suggest to cure low speed lean running? Boosterplug is not made for bikes after 2019, shame.

 

Hello Alf, grateful for your guide, I'm riding a 2021 Svartpilen, motor same as KTM 390, also paid/downloaded repair Manual; currently researching cure for lean and jerky fuelling on the Euro-5 2021 model. This spoils ride in urban traffic, on open road at high rpm bike is fine. Working through your numbers, appears that injection pressure is higher than the 3.0 Bar you quote; on the later bike already 3.2...3.7 Bar, possibly to improve emissions and fuel atomisation? Intend stripping the tank and pump, what extra pressure do you suggest to cure low speed lean running? Boosterplug is not made for bikes after 2019, shame. View attachment 54051

Hello Kevin. That is a good point.

You have to distinguish between fuel line pressure and fuel pressure regulator opening pressure.

Once the FPR opens the fuel pump is still capable to build some additional pressure on the line.

My experience is that 2019 and up KTM 390 engines FPR opening pressure is 3.0 Bar, but fuel line can reach up to 3.5 Bar.

In the service manual they specify a line pressure interval between 3.2 and 3.7 Bar as a normal operation range. This is because some factors as fuel pump wearing over time, battery voltage, fuel density (ethanol content, temperature...) have an impact on fuel line (rail) pressure.

If you want to get rid of low rpm jerkyness set your FPR to open at 3.5 Bar (using compressed air). If you do some additional intake and exhaust flow mods, go up to 4.0 Bar FPR opening pressure.

Your bike have adjustable FPR so you can use a trial error approach until you get driveability improvement...

Does your service manual say something about the injector flow rate???

Regards.