[natedizzer]

ok i've searched and read through alot of posts on backfiring but never really read a resolution.......here is my problem.....i'm running a HMF pipe, DJ 170 main jet and K&N filter.....my needle is set on the second notch from the top....1st question....when they say second notch..is that from the end that has the point or the end where you adjust the clip.....2nd question....when i'm at high RPM's and let off the gas a little bit (not completely), my bike starts to backfire and even shoots the blue flame.....what suggestions does everyone have to help me out with this problem......am i getting too much fuel or too much air.....i did adjust my a/f screw to 2 1/2 turns out......i'll check the plug to see what color it is as well but any help on this would be great.

 

[natedizzer]

checked my plug and its black around the threads but the place where the firing takes place is tan....just more info to help out and try to solve my problem

 

[natedizzer]

anyone have any ideas? come on guys help me out here

 

[rockclimber]

If I remember correctly when i jetted mine it was doing the same as your and mine was a little lean.Hope that helps

 

[Yooperforeman]

I think it's lean when they backfire out the exhaust.My old Big Red backfires on decell since I put a straight pipe on it.

 

[natedizzer]

help again

 

[Yooperforeman]

That 170 jet should be plenty.Check your exhaust system,make sure that all of the connections are tight and not leaking.An exhaust leak can cause backfiring too.

 

[KAGRIFF]

I am running a 172 jet. why did you make an adjustment on the needle setting? this i have seen cause some backfiring problem even though it should just help idle into very low range. never have adjusted them unless i had a major altitude change. usually it is a lean problem if it is backfiring out the exhaust at almost or at wot.

 

[KAGRIFF]

move you clip down a notch and it will richen it up some. if it is backfiring when you let off the gas it is to lean.