i just changed out my core on the st side, the guy that changed it for me passed away, he didn't get it running. the throttle gets a little tight around three quarters of the way. the motor starts and runs o.k. it sounds a little different though,its quiet and kinda bogs till it dies. and it doesnt kick up any rpms like the other one. the cables need to be set maybe? it has no power. i don't know if he took the cables off the carbs to change the motor. the new raves came with the core.