jetting i know not another jetting ? but

[YFZ450CW]

I know everyone is sick of jetting questions but i have searched first and couldnt come up with anything so i decided to ask but anyways i have an 04 yfz with white brothers aluminum pro exhaust and white brothers powerfilter and i used the jets they supplied which are 168 main and a 45 pilot jet. The machine backfires and im wondering what jetting specs i should go with now to correct and should i play with needle position at all? Thanks

[cals400ex]

turn the fuel screw out alittle bit. this screw will be located on the bottom of the carb.

[bwamos]

2 tests for ya.

1) Take off air box lid. (worse or better?) better means you're rich
2) Put lid back on turn on choke 1/4. (worse or better?) better means you're lean.

I agree with the above. You probably jsut need to turn in your air screw a 1/2 turn (clockwise).

righty tighty- lefty loosie. clockwise is in. he said out.:huh

[bwamos]

oops.. well backfire is usually caused by a lean condition. So screwing it in will reduce the air.. making it richer.