Hello from Greece.
I have a problem...
I have change my original oem cylinder and piston with this kit:Cylinder Works Big Bore Kit Honda CRF450R 488cc 450R,also the intake valves with steel valves and ofcourse i measure the valve exactly as the manual says,change the clutch kit with this:Honda CRF 450R/450X CRF450R 2002-2009 Clutch Kit Set.
Now when i push the clutch before the entry of a turn or going somewhere slowly with the revs down sometimes the engine stalls and only if a <close> the fuel,kick it 5-6 times <open>the fuel push the hot start,the engine start again.
i d like to say that the compression is really high and when the engine is cold after i kicked it 2 times with the air open the engine runs smoothly.
I have to say that at start i didn t set up the clutch lever correct ,after that the engine stalls again
Please do u thing that is a valve problem or i have to set up the jet and needles from the carburetor and how?
I apologize for my poor English
Skylos-mauros