Ole Green won't Run

[RPPerry3]

? This weekend I headed out to ride with my friends, it was just what I needed after a sucky week. Started the bike up after a few kicks. Choked of course. After several minutes of warming up I turned the choke off, slowly rolled on the throttle. Everything seemed good. I gave it one more good sharp twist and she backfired and stalled. I kicked for a long time, checked all the hoses, air filter, and even slipped in a brand new NGK plug. Had spark, a full tank of brand new gas, and the air filter looked good. After asking a few people the general guess-ta-nosis is that I may have jumped a tooth or so on timing. I did recently just replace the TOP END gaskets from head/cylinder to valve cover, and the automatic cam chain tensioner was put back in tightly. Your thoughts and advice are very much appreciated.

Thanks

-Paul 2005 KX250F

[D-K]

Check timing. If it skipped, change both the chain and the tensioner.

Also check if the sprocket has spun on any of the cams.

The hole in the sprocket should line up perfectly with the hole in the outer lobe.

[toomanytoys2]

Might also check the flywheel key. If the flywheel wasn't tight enough, the backfire could shear the key. It would still produe spark kicking it, but would be out of time.

[D-K]

Might also check the flywheel key. If the flywheel wasn't tight enough, the backfire could shear the key. It would still produe spark kicking it, but would be out of time.

True, and the taper has to be bone dry when assembling.

[kawasakirider550]

Also id check the piston, these kx250f are known for the piston cracking right down the center. Idk if that would have anything to do with it.

[Pr1malR8gw]

^^^ I agree if it's oem piston that maybe the cause.