Jetting help???

[MJ11]

My buddy just put a Dr. D carbon pipe on his '06 YZ450F. It is now backfiring and shooting flames at low rpm's like a champ. We live in Phoenix so average altitude and hot dry temps. All MX...any suggestions would be great, and yes he is going to join TT. ?

Thanks!!!

[x2stroker]

I would go with a 45 or 48 pilot and a 165 or 168 main.

[barch88]

Is his current jetting stock?

[MJ11]

Sorry, yes it is...should have said that.

[Fastest1]

Though I agree he should go up on the pilot jet size, has he ever adjusted the fuel screw? Go "out" in 1/4 turn increments.