400ex backfiring

[mames19]

i got a 02 with a whitebrothers slip on and a k n n filter, with a 148 jet and it backfires, whats the problem? bigger jet timing off? help

[leasureryan]

you have to change you pilot jet too! I suggest a 40 or 42....also, may want to try a 152 main

backfire on decel is lean on pilot circuit

[Hondamaster5505]

148 is stock, lol.

Try going to a 152 main and a 42 pilot. If it still backfires, play around with the needle by moving it one notch down.

I went to a 155 and 42 and most of my backfiring is gone.

the 42 makes it start so easy:D

[rideracelivemx7]

beh!! 148 with mods!? lol how does it run! haha yeah jet the hog. id go 155 or 160 with a 40 or 42 pilot. should run nice after you tune the fuel screw