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Discussion Starter · #1 · (Edited)
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 or 4.0 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 or 4.0 Bar FPR 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.

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(Note in the image above, left side, STOCK NEW STYLE ADJUSTABLE FPR, no need to buy nothing). Yes KTM new models stock FPR is adjustable. Guess why?
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Increasing air flow without compensating with more fuel lead to power losses, lean moistures, overheating, 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 or to adjust the new style one... 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.

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

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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 (moisture more complete burn, less emissions). Also it can last for 50.000km or more, so less frequent need to service it. (Note original spark plug at right side and iridium at left side: identical electrode protrusion on combustion chamber).

3.- Decat pipe: Arrow 310€

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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€ or less at AliExpress... (Note the second catalytic converter and also flow restrictive flattened tubing section on the original header...)

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.
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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.
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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€
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This is the best air box lid. It increases air flow to the engine and set the engine tone as a 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 failure 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. This mod registered only 1db increase at idle. 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: 450€ for 2020 & up models and 300€ or less for previous models.

Mattighoffen engineers made a superb engine respecting Euro4 emissions. I respect burning fuel in the chamber to make useful 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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lldlf, he did not and that is the issue.
Anyone can post anything they like but as long as they do not provide evidence its only a troll post.
Even reputable companies such as Coober have been whistled back on false claims.

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?
 

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Anyone can post anything they like but as long as they do not provide evidence its only a troll post.
One point for you, I just let a chance to this user to claim he does not spoofing.
@Alf, may you have any video from before and after your modification? Especially with the mid pipe replacement?
 

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Discussion Starter · #6 · (Edited)
Dyno runs are not budget...

The stock ECU works flawlessy with this setup. In closed loop it deals with the increased 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:


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

Lambda readings show no lean conditions...

Regards.
 

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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.
 

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Discussion Starter · #9 ·
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.
 

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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.
 

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2018 KTM DUKE 390/1980 DUCATI 900SS MHR/1979 HONDA F2 400/2016 YAMAHA MT-125/1953 BSA DBD34 GOLDSTAR
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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.
 

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Discussion Starter · #12 ·
It should be a horn always available on your bike, may be you don't need to be noisy all the time...
 

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Discussion Starter · #13 · (Edited)
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 use 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...
 

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2018 KTM DUKE 390/1980 DUCATI 900SS MHR/1979 HONDA F2 400/2016 YAMAHA MT-125/1953 BSA DBD34 GOLDSTAR
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It should be a horn always available on your bike, may be you don't need to be noisy all the time...
The excessive use of the horn (i.e filtering),is against the law in this country (Uk) . Whereas you are legally allowed a exhaust that has a no louder decibel level of 90 db.
 

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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.
 

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Discussion Starter · #16 · (Edited)
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 to 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 water pockets in the head). The larger ceramic insulator nose, the less heat exchange with the head cooling galleries, the hotter rate of the spark plug.

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

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2.- Is crucial to make sure that electrode protrusion on the chamber remains the same as original.
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You can consult a cross reference chart or rely on quality information as this site:

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.

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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,
 

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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?
 

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Discussion Starter · #18 · (Edited)
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
 

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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 :)
 

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Discussion Starter · #20 · (Edited)
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... ;)
 
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