Properly modded ( using proven combos ) , the power curve charting of the the 250 engine shows that it pulls hard past 9700 rpm and documented seat-o-pants experience proves a hard pull to 10,500 rpm redline cutoff. This phenomena, whereby redline cutoff is constantly, but inadvertently, hit during WOT accels, is due to the fact that an expected power drop-off never occurs.

 

Hello Mr. Marcelino,
I've read your post numerous times, and like the idea of getting a few more ponies out of my '09 KLX250SF. For some reason, I can't see the photos and graphs that you're referencing, maybe it's my stupid MacAir computer, or browser, or just me? You're write-up has more than enough detail, especially with you including the cam centerline, so I am sure I can do the mod without the pictures. How do you feelabout deleting the ACR?
Thanks,
Will

 

One more time... Camshaft Shootout: Lobe-Separation-Angle Tested and Explained it is as true on a small four stroke single as it is on a big V-8. Only difference is that they idle much lower and will notice the lumpiness of the narrower angle. Our 250s idle significantly higher, making it smoother and less noticeable, plus we pretty much live in the good zone of power gain. They have a comparable spread with 101° and 113° cams versus the Marcelino figures of 100° and 110°.

There used to be a great Engine Masters video on this work, but it's no longer on youtube. There are others though. It's nice to understand what is happening.

 

You can see the images in the link I have below. It's google doc and can be saved by anyone. If enough people save it the whole thing survives, unlike how the images of Marcelino's original post have been taken down.

 

2020+ klx300 ecu "detune" starts at 8000 rpm.. 500 rpm higher than klx250 EFI. But the logic is the same - retarded ignition and lower voltage on the coil.

 

I was thinking again about cam mod. Ultimately advance intake helps with low and mid power, retarding exhaust helps with high end power.
My experiment is inline with what advancing intake predicts. Maybe (I hope!) retarding exhaust will help with high end. I will do full mcm and measure it if I will have a chance.

 

I do not see any evidence of new KLX300 's having a muzzled (detuned) top end. The "uncorked" power curves do not show a detune - unless I have missed something ...

The "scientific" analysis of the MCM is simply childsplay to those rare individuals that understand the performance ramification of stock and MCM cam timings. While I do not consider myself an expert on this subject., the effects of MCM - advancing intake events + retarding exhaust events + increasing overlap - is not rocket science. Hint: Complete understanding of the "starting point" (the performance characteristics of the stock timings) determine what, and how much, can be done for enhancing VE via timing mods.

We are extremely lucky that simply swapping bolt holes and resetting gears in the chain provides timings that create such enhanced VE ( power)..

You've attempting to "understand" it, and failed. Now you seem to be on the verge of understanding the reason BOTH cams must be retimed. Progress, yes, but all is wasted time and effort on a proven mod.

The MCM is not experimental, it is a fully vetted performance enhancement. Do it correctly on any KLX and the entire power curve will be elevated - off idle to at least 8k rpm - with parity above 8k.

 

I don't know how you may missed it. It's on all dyno charts. Also check JH motor club vid and his conclusion - Torque cliff after 8000 rpm (exactly 8000.00, odd right?!) Whatever you do with the klx300 the top power will be exactly at 8000.00 rpm.

 

FWIW here is the explanation and the interesting part is that the MCM would actually lose power at low rpm IF - if it was done in a V-8 engine where low end is from arouind 800 rpm to 1200 rpm. The KLX is sitting there idling at 1250 rpm, so what should happen won't because it doesn't idle that low. From there, everything else in the video is totally applicable to ANY four stroke engine. The closing up to a narrower Lobe Separation Angle (LSA) will produce more power in most all of the rpm range of the KLX250. This is scientific mechanical fact, as noted by Steve Brule of Westech Performance Group.

Camshaft Shootout: Lobe-Separation Angle Tested and Explained... click here

The Motortrend video you want to view is:

Engine Masters Engine Personality Test: Camshaft LSA Explained

It can probably be found on Motortrend TV streaming or if you watch for it. I recorded and watched it two more times about a week ago. If one is looking for max horsepower then the stock setup or one with more lobe separation angle will probably do it, but the most torque is usually gained using a narrow lobe separation angle. The MCM is narrowing the separation angle.

 

Researching and analyzing the question of a programmed detune (via ECM programming) on the top end of the power curves. If present, only ECM reprogramming can remove it.
Will make new post with my findings and data.