I have a 1989 Quad racer, Fmf fatty pipe with powercore silencer, v-f reed cage setup, and mild drag porting, i had 240 main with 30 pilot pretty much stock jetting,,, i took it to a local flat track and burnt a hole in the top of the piston whoops!!! I really need some jetting help..... so i can make it to the races this weekend ..... with out blowin it again.... thanks.....

 

Mikuni carb??That jetting is good for 300ft. drag's,try a 280 main and redo the airfuel screw,and the needle clip should be in the middle.

 

I'm at around 300 feet above sea level, and I run a 270 main with the fatty pipe. The one big thing with those older original carbs is that the needle jet and needle wear out and tends to make the carb run rich, so people jet them down. If yours are the originals, then replace them and you can jet it correctly. If the transfer port windows have been modified (raised) then bigger jetting may be required due to a slower air velocity.