I own a 1988 Yamaha yz 250 and recently rebuilt the engine(bottom and top end). However I am running to rich as access oil is leaking from my exhaust and the bike will start with throttle and no choke(to much fuel). However after research I have found that my carb is from a 1998 cr 250. It fits just fine in the airbox and intake so no issues there. However even adjusting the air and fuel mixture I cant get it to run leaner and want to know if I need to change my jetting and if so how and which jets do I need? Thank you