Hello All,

My bike has been back-firing between gear shifts. It seems mostly to happen when I let off of the throttle and pull the clutch lever. Any ideas of causes that I can look for. Would this be normal operation for larger jets and open air flow?

K&N, D&D Exhaust, 150 / 40 jets, 2 washers, 3 turns on air mixture screw. No vacuum on petcock, no hose connected.

Thanks,
CB

backfiring out the carbs, or the tailpipe? people use the same term to describe both.

for carbs, my bike does it occasionally when cold, I just ignore it and it goes away 

for tailpipe, AWESOME AWESOME AWESOME. my GF's rx7 does this, and it makes me smile... though it could be related to a small exhaust leak and/or too rich of a mixture (maybe too many turns on the pilot, causing a transient right mixture when you throttle off).

tailpipe firing is usually a result of too much gas getting in there somehow, and then it finds air to react with while still hot enough for autoignition. The best solution is to rich up this mixture until you shoot foot long flames every time you shift gears.

leaky exhaust  ?

Quote from: ohgood on September 09, 2009, 01:31:49 PM
leaky exhaust  ?

+1 Maybee someone never put crush washers in where the exhaust mounts up to the cylinder? I would order some (or pick em up at the dealer) then pull the pipe off and check.

Thanks guys. I'm not much good with diagnosing a good running motor. I like the foot long flames idea as long as there isn't a damaging result. I will get new exhaust seals. I am still on the ones that came on the bike.

Yeah, they are one time use seals so if you took the exhaust off (which I recall you did) they need to be replaced.  I think they're about 5 bucks, and dealer should have them.