91 wr not running right

[yam*91*]

ok my bike is a 91 wr 250...its a beast (when its running right) i just rebuilt the top end new piston rings head gaskets honed cyl the works... the bike starts up first kick everytime no prob. but when i ride its not getting all the power it should its kinda boggin out but its not like its stalling. then after a couple mins of riding it seems like its getting better any ideas would be great

 

[inotocracy]

Have you cleaned the carb & air filter?

 

[rmc_olderthandirt]

The jetting could be way off.
The caburetor could be really dirty or out of adjustment (float level)
It could be starving for gas (clogged fuel line or stuck float valve)
Could be a sticky power valve.

When you rebuilt the top end, did you disassemble the power valve and clean it? Are you sure you put the linkage back together properly? Did you lock the linkage before you removed the nut so that you didn't apply the torque to down to the govoner?

Rod