Even more useful Alf, thanks. The factory special tool test tubing rig has a restrictor nozzle bleed off, presumably to mimic an injector, pump capacity is always excess to throttle body demand (my ultralight aircraft external pump shifts 130 litres per hour, but demand average 8l/hr). That system has an external Fuel Pressure Regulator with gauge in the tank return line, to keep closed until 3 bar is reached. On a motorcycle you could add a small FPR with separate return line to tank, but that would merely be 'short cut' by the internal tank Relief Valve, bleeding back to tank before it leaves out to the filter. More thought needed 🤔

 

In fact Kevin, it would be great using an external FPR and gauge setup. But you first will need to pull out the stock FPR.

This way you don't need to disassemble the fuel tank and pump assembly each time you want to try a different FPR setup...

You can do the tests on the bike to determine the FPR setup for optimal engine behavior and AFR. Once you have it, you can disassemble the external FPR and attach it to the compressed air pressure gauge and measure the opening pressure.

Then you can set the the stock FPR to the same opening pressure and install it. So you will have the bike back to stock...👍🏻

Does your service manual say something about the injector flow rate??? I need to confirm that info...

Regards!

 

Hey guys. Long time rider first time poster. I've been reading around on the forum and I finally decided to just throw in a "hello all from Southern California" as well as my own smelly arsehole opinion.

To Alf: (and regarding his budget/not-budget list and explanations) .... BRAVO.

I think a lot of you guys are spending too much time running around in mental circles with this stuff. The best part about cheap tricks is, well, they are cheap and anyone can try them out.

I really appreciate the new rider who wants to make his bike go vrooom all of a sudden but the best thing one can do is something my old coach taught me when I was coming up as a kid and it's the cheapest mod/performance trick of all
#1 Ride, ride, ride (on a track preferably but a well known stretch of twisty will do just fine too)

#2 Paper and Pencil (Journal) to jot down every little detail your little butt feelers tell you about what your bike is doing.

-Applying the above process to simple tweaks like Mr. Alf has shared are the best and most affordable (AND MEANINGFUL) way to judge how they work for your setup and skill level.

I personally was never much into the inner wizardry of the technicians around me, but because of the understanding I learned from my Sweaty-Butt-Monologues as a kid racer, I was able to make sense of all the various parameters that affect power gains pretty well.

Spending time wrenching on the bike is what its all about. I don't think there is just a perfect setup that any new bike owner will come across on a forum of his new bike that can tell him what to buy and who to believe. Get out there with your Ass, Journal, and toolbag and start playing around with it all and enjoy the freaking process of discovery while your at it!

Then all that money you save you can hand over to Ohlins anyways haha. Cheers guys.

 

FYI I run the 4,0 bar pressure regulator valve on my 2019. PT, Full Custom Titanium Polished and Ported exhaus.t Coober Filter Box. Bosche High Flow injector, NGK plug, (cat delete) and a lot more.

Fast. Unregistered. Cop Magnet and eager to tease.

 

FYI I run the 4,0 bar pressure regulator valve on my 2019. PT, Full Custom Titanium Polished and Ported exhaus.t Coober Filter Box. Bosche High Flow injector, NGK plug, (cat delete) and a lot more.

Fast. Unregistered. Cop Magnet and eager to tease.

What Injector do you use. It is for a 2023 RC390.
Thanks

 

Cant remember where I found the valve but figured the timing and fuel would be handled in WOT by the PT map so I went big. Pretty sure it was for an R1 or GSXR. Dude messured it for me before I bought it to make sure it would fit.

 

Honestly, I higher doubt you need a FPR if you are running the larger injector. I had to pull an absolute mountain load of fuel after installing mine.

 

I am working on the mapping throughout the week. I disagree though because no matter what the stock injector craps past 8k.

Just ordered another couple of the fpr's from Poland. They got to my house in soCal in 48hrs. Unreal.

Ill be throwing up some of my old dynos with different setups, but I really want to show the Torque live readings with the PT mapping as it's pretty much there and ready to get another run on the dyno soon.

 

I tried 3.5 bar regulator at the duke 200 but didn't notice any difference. Have you tried 3.5 or 4 Bar regulator?

Sent from my A80Pro using Tapatalk

 

Hey Alf, watcha think of this setup (from the booster plug thread):

Less restriction with the Comoetition Werkes pipe + More fuel with the boosterplug (richer) + More air with the Coober lid (leaner) would make for a balanced ratio. I hope it wont be too lean though if its true that in closed loop the BP is unactive.

Thoughts?

 

I'm concerned about being to lean with the airlid at high RPM as I understand the boosterplug only enrichens in open loop? Anyone..?

 

Here is what i think.pluggin in 3.5 bar fuel injector might help acceleration due to more gas ,but it should be measured.i dont think it will help more than maybe 0.2 0.3 seconds.you might disagree with me but ktm only gained 1 hp by increasing 25cc on 2024 duke.
i still back my thoughts.due to 373cc,piston and clyinder bore size,compression ratio bla bla bike is almost at limits.
what i believe is adding a slip on will reduce the weight and help accelation.rest modofications i dont think any torque or hp gains.
373cc,1 piston 45 hp is world record already like duke 690 75 hp record

 

They lose some HP with the strict Euro regulations as well and main thing - it must be A2 complaint, so limit is 35KW or 47HP anyways for legal grounds. So can't really compare what factory did and what is the potential here, as they have limits with output.

 

Hi, what "large" injector do you use for a 2023 RC390? I have full system , PT4 and FuelX pro, DNA airbox + K&N filter.
Track use only.

I had read something and bought a Bosch Injector:
Bosch Original Equipment 0280158233 Fuel Injector

But it didn't fit and not same electrical conexion...
I am competing against Kawa 400 and the are 2 long straights, and I can´t reach them...

So I don't know what else to do...
Just read the topic on the fuel pump FPR, but I am not sure how to do it. (How many turns?)

Thanks
Pierre

 

@Alf


Good Morning,


You seem to have a great deal of knowledge and common sense about you.


My bike is 2015 390 duke, So far I have changed the Filter to a conical DNA and have a 3d printed open lid mod, which seemed to make a really big difference.

I have a rekluse torqdrive clutch I will also install.
I will be changing the coil with MSD 8232 and using 8.5mm MSD superconductor wire.
Will this NGK LKAR9BI9 fit on this model bike?

Im looking at the thread on FPR should I change that also?
I had also Planned on getting the Grey area air box eventually with up rated injector.

Would you be able to share some comments here?

 

I would skip the FPR. No proof that is provides more fuel. An injector and a way to tune it is your best bet.

 

I did the FPR mod today for my 125. Let's see when spring comes - try to map it and then dyno in the end to see where we are.

 

Fuel Pressure Reducer/regulator? FPR.
I'm one of those crazy people not accustomed to shorts

 

Regulator, yes

 

Did first rides with the fuel mod. Definitely gets more fuel as engine and head temp are lower then before. Therefore more options with piggyback ECU to tune it further. Will keep you updated.

 

I actually made an account just to thank Alf wherever he is now. I did this mod and I can say that it does work. Just sharing my experience as it could help others.

My bike is a Husqvarna Vitpilen 401 which is just similar to the Duke 390 but in a non-orange dress. I have the following mods:

Airbox: OEM high flow air filter + DNA Stage 2 Lid
Exhaust: stock header with 1 of the cats removed + chamber delete (custom db killer) + short Austin Racing GP1 muffler (with perforated-style db killer inside the link pipe)
Fueling: FuelX Pro+

I do want to point out that the custom db killer I installed inside the chamber delete is a funnel-like design with slits perpendicular to a central smaller hole. Before I installed this, I lost power at low RPMs like many do when they opened up the exhaust. I think it's because of too high scavenging and no backpressure that fuel-rich air is just getting sucked out. The custom db killer I made adds the necessary backpressure at low RPMs but it also allows more exhaust to flow out when the engine revs higher due to higher pressure. It essentially acts like a pressure-sensitive restrictor. With it and in combination of the FuelX Pro+, I got great low to mid power and torque and gradual power production up to high RPMs. But still, there's still not enough fueling at higher RPMs so the engine momentarily bogs down when shifting up while at high RPM or when suddenly going WOT from steady or low revs. Increasing the setting (7-9) on FuelX Pro+ helps decrease the bogging but can't really eliminate it as it only works at closed-loop up to mid throttle (this is the Pro+, I think extra fuel is dumped just before the ECU switches to open-loop).

My initial option was to get the bike dyno tuned and have the ECU reflashed but I don't have the time to travel to the tuner at the moment and I want to install titanium retainers first. And that's when I saw Alf's post and decided to try it out and treat it as training for when I try to get to the valve retainers (I do all the maintenance and mods on my bike myself).

So I got into it and I have the new style FPR. From my testing, it seems mine was set to 3.2 bar (air) which approximates 3.5 bar (fuel) already which could explain why my bike didn't have stalling or jerkiness when it was all stock and ran even better when I did the muffler delete and installed a high flow air filter.

Anyways, from my testing, I found that every turn on the FPR resulted in a 0.24 bar change. So I initially adjusted the FPR by 1.25 turns to get 3.8 bar (fuel) pressure. Test rode the bike and it was indeed effective as the bogging was almost completely gone, only happening when I was exiting a corner at high speed and high rpm then shifting. It was just a second or less. Low-mid RPM performance was more punchy too and I didn't have to raise the FuelX setting and it stayed at 6. After that, I got the FPR out again and adjusted it with an extra 1.5 turns which resulted in 4.1-4.2 bar (fuel) pressure. Did an even longer test ride involving a long stretch of highway, twisty mountain roads, and even a little light offroad. And the result? It was almost perfect. The bike ran its best yet. No bogging at all but there's one catch, the engine feels like it was choking at the highest RPMs. I suspected that some exhaust can't completely evacuate at very high RPMs now so I modified the custom db killer on my chamber delete for a little extra flow and it worked. Now, the bike has improved power and torque throughout the rev range. And I love the fact that I can fine-tune the fueling with FuelX for either performance/aggressive riding or economy/comfy riding as higher settings make launching and sudden throttle inputs more punchy while lower settings make launching gentler (important for my backpack) and less fuel during cruising at steady speeds.

I can't provide AFR numbers or dyno data yet as what some would demand but I can (anecdotally) attest to the fact that the FPR mod/tuning eliminated the lean condition symptoms my bike had. It's not as refined as getting the ECU remapped but it is a free (but tedious) way to influence your bike's fueling if you kept track of your mods, understood their effects to airflow, VE, backpressure and scavenging.

From my understanding and research, this mod only is effective at open-loop as the ECU's stock fueling map only really tells the fuel injector to engage at a set pulse duration for a set throttle input and RPM. It doesn't really know how much fuel was injected. Changing the rail pressure via the FPR changes the amount of fuel actually injected. Higher pressure, more fuel squirted vs lower pressure at the same pulse duration. So it does make the AFR richer than stock. During closed-loop though, the ECU will use the O2 sensor's readings and do the necessary trims. This is where FuelX will do the trick by literally tricking the ECU with a nudged O2 reading.

I will still get my bike dyno-tuned and the ECU reflashed once I get around installing the titanium retainers. But for now, the bike already runs superb and I just want to thank Alf again, wherever you are now.

Sorry for the long comment and sorry for reviving this old thread.

 

Thanks for the input, always good to hear from someone who is thinking about what he is doing. Will be interesting to see what the dyno says once you get there.

 

I will definitely post results once I get to it. Although I have no baseline to compare it to as I didn't have it dyno'd stock. Though I think what would be interesting is how much the tuner would need to adjust the ECU map. If he doesn't need to do as much adjustments then I guess that will be enough data to support this mod. It's just a bit far away from me and I have to get into the engine and install titanium valve retainers first when I do the valve clearance check at 15,000km. Right now, I'm at just over 10,500km. I went on a ride again this morning and to my surprise, I reached 120kph top speed in 3rd gear. Just before I messed with the FPR, my bike can only reach 118kph and it was struggling. Now, it just went up smoothly. When my bike was completely stock, I think I only reached 112kph in 3rd gear.