lost power

[sarg]

have 03 250f. approx 40 hrs on bike. 25 in trails, 15 on track. well maintained. clean filter, oil has been changed 13 times. new clutch. has been down on power. bike starts well and runs very clean.i'm trying to eliminate possibilities- repack dr.d, new plug etc. i've never checked valves but i will take it in to have them checked.i hope i dont need a top end. how many hours are people getting before a rebuild? any one have any suggestions? on my past bikes [2 strokes]iwould throw a piston and rings in. i have afeeling that this may be neccesary.if it is i'm selling and buying anew one!

[barton]

Air filter clean, with no obstructions in intake? Change spark plug? Exhaust choked? Carburetor clean?

Just some things to check. Do some testing and give us some more specific information. What maintenance/service/modifications have you done lately?

[gonzo]

I would check the valves. Do them yourself it's very easy. Just pop the valve cover off and stick the feelers between the valve head and the cam. Start very small and work your way up till you can't fit between then the size before was your clearance. Replace valve cover your done. You may not have to reshim and why spend the money for nothing.