cj600

I have a 94 zr 580,anything before 5,000 rpms she just boggs down once it hits 5000 rpm it takes right off full power,Now ive rebuilt the engine 2 times,had the carbs tuned,then tried a different set,still didnt work tried 2 CDI's,coils,2 different primary,secondary clutches,Belt is good on it. Carb saftey switches are disconnected because the sled wouldnt run with them plugged in.Fuel system is fine,good compression,excellent base pressure,I cant figure out whats wrong with this sled if anyone has any ideas please let me know.I ran 1 finale test and when i had the crankcase out i fill it with liquid on one side. i dont know if it is suppossed to leak from one side to the other and if it is how fast,The only thing i can think it might be is the crank center seal.