exhaust and rejetting?

[antonovich]

Ok guys i got the bike running pretty well with the full vance, the k&n, and the jets.  The only probem i seem to have is that the bike backfires a decent amount when downshifting/engine braking.  Any idea's what the issue is? 

[NiceGuysFinishLast]

is it actual backfiring, or just burbling that's deeper than you're used to?

[Wrecent_Wryder]

You gotta tune, sorry to say....

When I first went to the new exhaust I installed 150 mains, and had a LOT of popping and burbling on deceleration.. enough so that it was sort of embarrassing. There is always going to be some with a performance exhaust, but this was scaring people. Later I switched to 147.5 mians, and most of it went away, what remained was a lot quieter.

Just recently, in an attempt to improve warmup, I switched from 22.5 pilots to 20, and again, got a lot of popping. This sounded sort of different... less burbling, angry, sharp. Yesterday I went back to the 22.5 pilots.

So, I cured the problem once by reducing the size of the main jets, and another time by increasing the size of the pilots. Not very helpful, sorry.

Keep in mind that when compression braking at 8,000 rpm, the throttle is in the same position it is at idle in a parking lot- butterflies closed, trying to accommodate whatever's going on with the pilots. That's huge range of conditions.