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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.
 

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Discussion Starter · #22 ·
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,
 

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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,

Completely agree, but for now it's something and gives me data on its effectiveness. I just got it in today.
 

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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.
 

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Discussion Starter · #25 · (Edited)
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,
 

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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 unburn washing oil film from cylinder walls and induce premature engine wearing and reduced compression.

2.- Increasing fuel line pressure provides better fuel atomisation, wich improves idling and get rid of 0-4.000 RPM (intake manifold low air flow velocity) jerkiness on the stock bike. This is what I have also observed on my bike: better driveability. Considering people spend 500€ on piggyback ECU plus Dyno runs to get rid of driveability issues on this bike, you should agree that a 3,5 BAR 45€ FPR is a pretty good approach...

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.

Why won't you recommend this mod??? This FPR mod achieved what your "mithical expensive" piggyback ECU was unable to do.

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 (thousands of hours on factory bench dynos)... If you have to adjust the tune of your piggyback ECU every time westher changes may be you are doing something wrong , or that ECU is just crap... This is why 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,

Running an open-air intake setup, Power Commander V, and data logging and tuning done by myself.

Fuel Pressure would absolutely have an effect on AFRS and the fact that I didn't see any real changes in my data log doesn't lead me to believe that anything of value is happening. I for one have the ability to watch how my bike is actually running. The question at this point is do you happen to have a means of doing so? I am fully aware of what fuel washing can do to the cylinder, I've been running this exact setup for 23,000 miles so far with no issues.

The honest truth is I actually found some cells that LEANED out compared to my OEM 3 bar setup as well. Your process of doing an IDLE relearn would be correct and I usually recommend that process to others as well. While an ECU can adjust I went from extremes in terms of weather shifts. From 90-95 degree weather to 20-degree weather. My adjustments were simply to clean up the fuel map a little, especially after installed that 3.5 FPR after it leaned out a few cells. These have been corrected already.

Now, I did consider the effectiveness of this setup on a stock bike setup. I would be interested to see what information you could actually provide that proves that it works. I am not ruling out your statement that having a fuel tuning computer could be skewing my results, but I am saying that from my standpoint I have not seen any changes.... So we are pretty much at a He said, She said kind of situation unless you have actual data to provide that supports your end. I for one actually want to believe that this works, that is the main reason I went ahead purchased the setup to try it out. I look forward to seeing your results.
 

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Discussion Starter · #27 · (Edited)
Running an open-air intake setup, Power Commander V, and data logging and tuning done by myself.

Fuel Pressure would absolutely have an effect on AFRS and the fact that I didn't see any real changes in my data log doesn't lead me to believe that anything of value is happening. I for one have the ability to watch how my bike is actually running. The question at this point is do you happen to have a means of doing so? I am fully aware of what fuel washing can do to the cylinder, I've been running this exact setup for 23,000 miles so far with no issues.

The honest truth is I actually found some cells that LEANED out compared to my OEM 3 bar setup as well. Your process of doing an IDLE relearn would be correct and I usually recommend that process to others as well. While an ECU can adjust I went from extremes in terms of weather shifts. From 90-95 degree weather to 20-degree weather. My adjustments were simply to clean up the fuel map a little, especially after installed that 3.5 FPR after it leaned out a few cells. These have been corrected already.

Now, I did consider the effectiveness of this setup on a stock bike setup. I would be interested to see what information you could actually provide that proves that it works. I am not ruling out your statement that having a fuel tuning computer could be skewing my results, but I am saying that from my standpoint I have not seen any changes.... So we are pretty much at a He said, She said kind of situation unless you have actual data to provide that supports your end. I for one actually want to believe that this works, that is the main reason I went ahead purchased the setup to try it out. I look forward to seeing your results.
I advised you that using the stock narrowband lambda O2 sensor, will not provide accurate tuning. To do what you want to with a piggyback ECU, you need Dyno runs and wideband lambda datalogging. And that is not budget.

Without an accurated tune, you don't have a reliable starting point to evaluate any mods. Extreme weather conditions are not good for tuning nor to take conclusions for the average bike.

Let me insist: When in closed loop operation, AFR won't change. Closed loop target AFR in stock ECU are for emissions and fuel saving, not for power. So if your piggyback ECU can't command closed loop (PC5 cannot) no big changes will be noticed, but this doesn't mean nothing is happening, more air and more fuel are delivered but to match a lean AFR target. FPR tuning is for open loop (@ WOT). This is because in open loop, when you increase the fuel line pressure up to 3.5 BAR, the ECU is 'dumb' to this fact and will produce the same injector pulse duration as it expects it would if the pressure was 3 BAR.

Providing accurated data on engine mods is not easy, and I prefer not to show any data right now. The only thing I can tell you is that stock lambda readings show no lean conditions on my engine. If mods I installed (airbox lid / exhaust decat) allow to more air flow and the engine doesn't show lean conditions, additional power is being made. That's all by now. For 300€, most people will call it a day... But we have to put finger on the sore...

I will provide accurated data, but I have to get the bike back to stock, see the best way to attach a wideband lambda, find a reliable Dyno and all that stuff you didn't get done...

So let's switch to PLAUSIBLE???🤣🤣🤣🤣🤣

Regards,
 

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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...

fuel diagram.jpg
 

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Discussion Starter · #29 · (Edited)
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...
52979

Regards,
 

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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€

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€

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€

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€

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€

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€

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€

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:


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.
 

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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?
 

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Discussion Starter · #32 · (Edited)
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?😁
53510

53511

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.
 

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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.
 

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Discussion Starter · #34 · (Edited)
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).

The ECU controls injector puse 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.
 

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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.
 

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Discussion Starter · #36 · (Edited)
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.
O no, no, that is not my opinion. Is what intelligence agencies of the free world are saying: CIA, MI5, MI6... Trump said that, and now Biden is also saying that... 140.000 people died in Spain by COVID-19 and that is not an opinion IS A FACT, my family knows it. You can apply your RED CENSORSHIP, but the facts are still there. What do you think is more difficult: demonstrate that China made it, or China compensating the world by the hazard created at their Wuhan labs??????

Sorry, if I bothered you, sometimes I forget you can't express freely at your country. I don't understand why this forum chooses as "super moderator" someone that isn't used to a democratic environment. Maybe is time to quit... 😘

Good technical knowledge and science cannot absolutely be degraded by facts... As I said, keep calm and enjoy you bike...
 

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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.
 

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Discussion Starter · #38 · (Edited)
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 make 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...
 

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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.
 

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Discussion Starter · #40 ·
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.
 
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