Okay i hope someone has had this encounter before right after rebuilding the engine. Okay so i took the engine out to have Don Lackey put all new internal parts. Now this is happening to both of my bike with new internal rebuilds. I have a 2004 yz 250 and a 2003 rm 250. I could never figure it out with my yz 250 but it wasn't that bad. Recently i just put the rm 250 engine rebuild back on the bike and test drove it. This bike is doing it real bad and the more i ride it the more it gets angry and starts to idle high, and as it settles to idle it surges. My yz 250 did it but was minor and at 18 hrs i think it blew a ring. So im waiting to take it apart and now my rm is the issue and it's bothering me cause i dont want it to blow up. Can someone give me some tips on what to look for! Could it be my reed valves (was running fine before rebuild)Help!

Never had this problem until rebuilds!

Have you not talked to Don about it. This is the reason I don't remove the engine any longer. It took me longer than it was worth. Let Don do it all...

I say it's some sort of lean condition and I'm an expert since I once went through a Cat 3406B injection pump and I rebuilt a hemorrhoid valve on an old mechanical Mack. The next guy might suspect the muffler bearings since his 30-something year old cousin that looks like the Real Slim Shady once had a problem with his muffler bearings.

I'm with Fender Bender...Call Don! He is a real nice guy. He knows his stuff. AND he knows the bike, or atleast it's engine.