I need help badly....I have basically a stock motor. It starts first kick everytime & idles perfect. It takes off fine with no bogging or nothing. A perfect bottom end, but its when I get to about a 1/4 throttle thru W.O.T. It sputters, break up, spit back, backfire, & has no power at all. I know its the jetting, but I dont have a clue to what size larger main jet to start with. It will only run 69-70mph the way it is now with a 1/8-1/4 throttle. I checked for air leaks & the motor is tight.
My setup is:
Coolhead w/21cc domes
Wiseco pro lite pistons
V-F 2's reeds (reeds are new)
Boss Racing intake w/ built in crossver tube
34mm Keihin PJ carbs (#55 pilots / #152 mains
Dual K&N filters w/ airbox removed
adjustable timing plate @ 0 degrees(stock)
RM Stator (stator)
RM Stator adjustable CDI box
16T-40T sprocket gearing