jetting help

[sl2fast]

or atleast i hope its jetting, first off 96 300ex, mods full white bros e series exhaust and k&n filter. thats all i know of motor wise. i bought it and it hasnt quite run right since and ive been tinkering trying to get it to idle right. it constantly backfires through the carb. ive tried a couple settings on the mixture screw which i got it ok but still backfired like a mofo. so i pulled the bowl off today and it had a 116 main and a 40 pilot. if i had to make a guess the 116 is pretty small and the 40 pilot is a bit big. should it have a 38 pilot?

if its not jetting, could it have jump time?

thanks
T

[Tommy Warren]

your pilot is fine its you main:eek2: the stock size is a 122 and you have a 116 with a pipe and filter?:huh you need to get a 128 main and see how that works.

[sl2fast]

but what does the main jet have to do with the idle tho? when i rev it the revs linger high then slowly come down. i had my stock 122 main from my old 300 that i tossed in it and it didnt make one slight difference

[born2ride14]

you are probably using a dino het kit. put in the 128 in with a 42 pilot

[QuadCobbler]

It sounds to me like the timimg is off. Motor is porobly firing when the intake valve is open, causing the backfire through the carb. If the bike is old the timing chain could have stretched, or tentioner could be bad leting it jump time.

[sl2fast]

looks like timing is off a tooth or two, fix that and check compression of this pig to see if anything else could be messed up