loss of power/backfire/spluttering at high revs

[joey000]

I have a pitpro with a 155z engine, 2 rides old, i did run it in fairly hard but not to ridiculously, its got new oil in it, new spark plug, unifilter, first 2 rides it was fine no problems at all but when i go to start it now it will lose power at high revs almost as if its not getting enough fuel. im not very farmiliar with carburettors (im assuming thats where the problem is) so if anybody could help me out id be much appreciative thanks

 

[Cactus Jack]

Check your valve clearances ... New valves settle into the seats during run in and can sink a few thou ... enough to cause your described symptoms ...

 

[joey000]

thanks for that how would i go about doing that? thanks

*edit just read the tutorial and i dont have the tools required to do it :|

 

[heathmynhart]

Hey mate, Did the valves fix your problem? I have the same issue, but have reset the valves and changed the carby needle position.

Think i might need a bigger main jet?? What did you end up doing?