250F kx 250 f low compression

Hello i have a Kx 250 f 2004 4Stroke with a 50 Psi Compression and the bike doesn't start, i' ve changed the top/end gaskets and adjusted the valve clearence to stock specs, cylinder and piston are in a perfect condition. what should i check next?


Staff member
I would clean the carburetor really good. Check for spark.
Starting fluid sprayed down the intake should make it at least show signs of life.
-BIG DAN:thumb:
The piston rings could also be worn down, throw a little but of oil down the cylinder and do a compression test again, if you get more you’re rings are worn, if theres almost no change then the rings are good