Yep, wonderful work done by Beaver County Bike works... wonder why they are out of buisness now..

 

I would have liked to document thigs more but unfortunatelly I can´t afford it , I´m in between jobs right now so even the 50 euros for the dyno was a big effort for me . I wil not go hungry to satisfy some academic curiosities . I´m an electronics engineer and i´ve been working most of my active life in the automotive field . I ´ve prept many engines for drag racing while I was livig in the states and a few cars for a spanish championship . I´m familiar with many many cam timings , this mod did not appear to me in a dream .
If you think Kawasaki was trying to tune the KLX engine for maximum performance , you´re wrong , this engine has a state of tune such that it can run reliable , on garbage gasoline , in any corner of the world and pass emisions too in the countries where is required too . The KX250 F is tuned for maximum performance , it has 35 HP , the 25 HP I´ve got on the KLX are nothing in comparacing with a KXF .
Before posting the mod in any forum ( spanish or english ) I´ve tested the bike in town , on mountain pases , on trails , on the highway and o the dyno for some 7-800 Km , nothing negative to report , just more stones and the same fuel consumption .
Before posting this mod I´ve had various frieds that told me I should make money with this mod . I didn´t listened to them , I´ve put it in the wild as free knoledge .

 

Looking at bikebandit.com, the camshaft sprocket has 32 teeth. Maybe it´s a typo.


Could you go in more details on how to exactly "retard/advance the camshaft 2 teeth in the chain"? Does the piston need to be at a certain position before everything is moved around?
I´ll be on vacation all month in July and I´m considering taking my D-Tracker to my dealer to get this done.

 

Fantastic work!! Can you give us an idea of how hard the bike pulls now in comparison to before the modification? Are you still using the stock exhaust?
Thanks

 

Thinking of doing only the intake tomorrow. See what happens. I am curious about cold and hot start, smooth idle and power.

I totally understand the setup, moving the cam by 1/2 tooth in the end.

OK stupid question. Could I move the chain by one tooth on the crank that results in 1/2 tooth on the cam?

Davied

 

Allways when working on the timing put you engine to TDC , your cams should NOT be pushing the tappets .
After you position your engine at TDC , remove the chain tensioner , the chain ( make sure it doesn´t fall) , remove the cams . Mark the position of your decompressor ( ACR ) , you will need to press it out and reinsert it 6-7 mm ( 1/4 ich ) rotated counter clock wise as you look at it .
For the intake shaft : take out the 2 sprocket bolts , turn the sprocket util the EX holes allign with the threaded holes in the camshaft , put the bolts in and tighten , use threadlock . When you put the cam back in you NEED to put it two teeth turned CCW as you look at the sprocket , on the left the IN mark is a little below the edge of the head , on the right of the sprocket the mark is exactly 2 teeth above the edge of the head . Look carefully at the fotos .
On the exhaust shaft is exactly the same , but on the opposite direction .
Move the bolts to the IN position and put the shaft 2 teeth rotated CW ( Clock Wise ) .
Reset your tensioner , install it and then turn the engine BY HAND a few times
to make sure everything is OK . Then you can recheck your new allignement .
Add gasoline and enjoy !

 

I think you're wrong here Larry, advancing the intake valve reduces the piston to valve clearance. Remember that the intake valve starts to while the piston is moving up. At TDC, the intake is already open may be 20% of its lift. If you advance it, it will be more open when the piston is at TDC.

On the other hand, you are right that the intake side is more secure than exhaust: the intake valve clearance is not affected by valve float, contrarily to exhaust side. Even though the engine is designed to operate without significant valve float up to redline, there might be a small amount at very high rpm. That amount increases with time, due to valve spring fatigue. The exhaust valve to piston clearance decreases when valve float becomes larger, because the piston is moving up when the exhaust valve closes.

Did I made that clear? I'm not sure I would understand myself if I read this back

Overall, I'm sure the timing Marcelino suggests decreases the piston-valve clearance for both intake and exhaust, but I would be very surprised if it became an issue. People are putting new bores with higher compression since a long time already, indicating the OEM design leaves ample room for improvements.

 

Thank you. BTW, is your real name Marcelino? Mine´s Marcelo.

 

Your correct Ray. I was not thinking about the pre TDC valve overlap part of the valve motion timing. Together, we almost make one smart dude! Not quite, but almost!

 

@ Malves
My full name is Marcelino Carne y Vino .
In the papers they put Marcel .