JDM unrestricted ecu seems doesn't have major flaws! And it's not about fuel management.

I considered using Apitech aftermarket ECU which can adjust ignition, fuel, etc. But
1) it's board not reliable
2) in racing aftermarket ECU typically nobody cares about engine safety - knock monitoring, fallbacks for malfunctioning sensors and so on. OEM ecu does all that.

 

@tsc , you've mentioned knock sensing/monitoring several times now. Unless I've totally lost it ( which is possible ) , the KLX 250/300 has never incorporated a knock sensor.

 

Hm, you are right, there is no knock sensor! For some reason I was thinking it's there...

 

I have the ApiTech standalone. It was great the last 6 months but I just took it in for a dyno tune and now there's an issue the mechanic can't solve (yet). I'll let you know if it gets resolved. I'm on my 3rd ECU now, so may have to go back to the EJK or, regrettably, turn it back into a 250cc.






Current issue mechanic trying to solve:

 

Assuming you have a lid on the airbox and some kind of snorkel, those curves look very good.
You can't make top-end power with the lid on the airbox.
Your AFR is too lean ( as usual, and usually due to ignorant "tuners" ) , keep WOT AFR below 13:1 - best is 12.5 t0 12.8 ..

What is the problem yall are experiencing ?

 

Yes it has the lid and bigger snorkel on. Do you think I should try without it?

I previously had a very loud exhaust on that became impossible to ride with once the 330 kit was installed so put a quieter exhaust and fitted the lid again. After doing this I thought I did notice a loss in top end.

I've messaged the mechanic to try get a clearer idea of the issue and showed him your input on the AFR.

 

The feedback I received is as follows:

afr depends on gasoline quality, in vietnam usually 13 is for maximum power, based on maximum power to set afr level. there is dyno to prove what is ideal afr in vietnam,

The ckp sensor seems to be interfered with, automatically losing signal so the ecu will automatically increase rpm abnormally so the fuel is injected out of order.

I need the stock klx 250, to cross check, about the ecu and ckp sensor

You can sent him this video


Automatic change position

 

I understand that the tuner is saying the signaling from the crankshaft position sensor seems to become corrupted during the dyno runs. I understand that the tuner is saying that the result is an abnormal rise in RPM.
Unfortunately, I cannot help with this issue except to suggest that such an issue is certainly rare and probably caused by failing component(s) on your bike and/or a fault (or faults) with the tuners' equipment/software.

With the dyno proof posted for all to see ( in here) , All KLX owners should, by now, understand that the upper 1/2 of the powerband is completely governed by the airbox lid.
Removing the lid will allow tuning that can produce power all the way to redline.

Regarding proper AFR targets for WOT power production :
%99 of all tuners believe 13 or 13+ is best for WOT power production. Your tuner is simply another brick-in-the-wall on this subject.
The %1 ( that seem to actually understand AFR burn rates and flame front propagation rates ) are the tuners that produce "magical" power numbers that no one else can.
Thru the years, I have tried to find the reason(s) for this "flawed 13:1 doctrine" . Basically, Tuners are business owners, they are NOT schooled in thermodynamics - so I know they are "following a doctrine" they've "picked up" from somewhere.
The only clue I've found, for this dogma, is that the DynoJet software ( that runs on the DJ dynos) has a default AFR set-point of just over 13:1 on the AFR chart and charting function - and ALL tuners leave this default setting in play.. I'm convinced that tuners believe this default setting is "gospel" for targeting with tuning. I'm convinced Tuners are clueless as to how to set up the DJ software.

Studying AFR brun rates and flame propagation rates is not for the "faint of heart". I researched for months before I read enough doctoral thesis' and white papers to gain actual knowledge on the subject.
I also wanted to understand why dogma spouts " stock tunes are too lean" , when actual dyno data almost ALWAYS shows stock tunes have OVERLY RICH fueling @ WOT, especially in the top end RPM range.
In a nutshell, the reason is Component Protection - "overly" rich top WOT fueling provides a safety factor for engine longevity thru cooling the engines' top end components.

Recently, I achieved a BIG WIN on the issue of AFR targeting thru a tuning project I managed on the Indian Motorcycle forum. Showing that 12.53 outperformed all others, the industry adopted my findings.
Anyway, you will not be able to change your tuners' mind about WOT AFR targeting. All you can do is tell him you really prefer your bike to be fueled at 12.5 to 12.8.. Who knows, maybe he will do this for you, and learn something in the process !

 

In fact when I was dyno tuning I haven't seen much difference in hp numbers within the AFR range 14:1 - 12:1. But more fuel is safer, so I try to stick to 12:1.

 

Thanks mate. Yes he is open to doing as I suggest with offerings from the forum.

I'll see how it goes. Yesterday, he had Keng Engines on the phone to assist, who pointed out some of the values are wrong. As far as I know, the API software is difficult to use without any support.

He's also removed the lid because I noticed a loss in top end when putting it back on last time, although there were a few other factors such as the ApiTech ECU instead of EJK, and also a quieter full exhaust system... The Two Brothers had me bleeding from the ears once it was running with a 330 kit.