426 motor reving on its own and no power after half throtol

[yz426ex]

the motor ran fine and then i put a power now valve on it and a boysen excelerator pump cover on the carb.

now if i give it throtol over half throtol it just bogs right down. low end is still pritty good but when i shift some times it bogs a little for a sec.

also some times when im coming into a turn and pull the clutch in it will start to rev on its own then it will stop after a couple seconds. soooo....... What up? :|

should i put a bigger main jet in it?

 

[biglou]

Sounds lean. Could be an air leak, too. Check for air leaks, then bump the pilot up one and try it. Or maybe go out another turn on the pilot screw. I'm not a big fan of going more than 2-1/2 turns out on it before bumping the pilot jet, however.