I will post this here, hoping maybe someone out there has run into a similar problem. The engine pulls pretty strong in a very narrow rpm range (mid range), but will not rev out cleanly. Due to other mechanical issues, it has a complete new engine (including carb, stator, reed cage, etc) but this problem has remained. The only pieces remaining are the FMF pipe/silencer and the ignition coil/wire/ignition box. Before I spend more money chasing this demon, has anyone else out there experienced this with a 250R? Thanks guys!