Straight Pipe Tuning !

[Zook]

The pilot jets are the ones you should be most concerned with since those are the ones in use most of the time. The mains only come into play at about 3/4 to full throttle.

Backfiring on decel is a lean pilot. The throttle is closed, so the mains have nothing to do with it.

Saving a lot of lives with that thing, aren't you?

[chef1366]

Actually your main comes into the picture as soon as the needle rises out of it.