backfire

[f150mann]

i put a hmf slip on pipe on my 400ex, and changed to a 155 main jet, it pulls good, sounds good, no bog. but on the decel is backfires fairly loudly. is this a pilot jet problem??? or is my main not dead on?

[honda300EXtreme]

main jet controls 3/4 - wide open

id throw in a 42 pilot and then tune the air/fuel screw from there

[f150mann]

well it has no problem on accel from 0-full, but on decel from say 3/4-0 it backfires, maybe 1/2-0, not sure

[honda300EXtreme]

yea that means your lean on your pilot circuit, i would up the pilot jet, but if ya dont wana do that yet you can play with the air/fuel screw and that should all but eliminate it..

i would back it out about a half turn,,, and if it still pops a quarter turn from there and so on at quarter turn increments...

[JOEX]

Originally posted by honda300EXtreme
yea that means your lean on your pilot circuit, i would up the pilot jet, but if ya dont wana do that yet you can play with the air/fuel screw and that should all but eliminate it..

i would back it out about a half turn,,, and if it still pops a quarter turn from there and so on at quarter turn increments...
There is a limited number of turns you can go before it falls out...

[zdowell]

A little backfire is common though... My pops a couple times on deceleration. But, id try what the guy above says if its that bad

[honda300EXtreme]

Originally posted by JOEX
There is a limited number of turns you can go before it falls out...

very true... i forgot to mention that :rolleyes:


but if you have to go more than 2 full turns out,, its definatly time to bump up your pilot jet.

[f150mann]

i will give it a try tomorrow guys, maybe ill even get a sound clip so you can see, maybe its normal, just doesnt seem it to me