Latest project is a 86 TRX250R, but with a 86 ATC250R motor. Slow jet is #42 & main jet is #145(both stock according to Clymer manual). I have a Curtis Sparks pipe(can't get in touch with Mr. Sparks for help) & am planning on installing a K&N filter with no airbox. What would be a good jet # to start with?? All help appreciated.

 

no airbox? go way rich...like 170+...and is this with the stock carb?