300ex backfiring

[brettg]

my problem is that i have a 2000 300ex with e-series slip on and K&n filter with the lid on. I rejetted to the dynojet 118 and adjusted the needle settings for my elevation(below 3000). I noticided its running decent, but the exhaust continues to abckfire after i ahve already rejetted. So i called White bros. n they told me to decrease the # of discs and it would richen up the mixture. Instead fo 12 discs i now have 10 and it seems as if the backfiring has gotten louder and has more of a pop to it. My question is how i can fix this problem or if i put 11 discs on instead of 10, if that will help...........Also i think their is a small crack in the headpipe, which i think may also have an affect on the engines performance and possible add to the backfiring.....


Any help will work.

Edit: it backfires after a strong deceleration. but does nto when i accelerate hard

[Sparky_20]

when is it backfiring? If its on decel then you need to put in a larger pilot jet. If its happening all the time then I would reccomend moving your needle clip down one notch (if its adjustable) or check for other reasons that your not getting enough fuel. Possibly your fuel petcock is getting a bit clogged or your carb is gummed up. Its also possible that you have an air leak, make sure all hoses and clams are good and secure.

[brettg]

its on decelerating but im not sure if its due to the minor crack in the headpipe where it connects the the cylinder. i mite jsut buy a new headpipe and see if that works and if not im going to bring it to the dealer.. i also took 2 discs off the e-series so now its 10 instead of 12 to richen the mixture up

[Sparky_20]

its possible that its the headpipe but on decel, the slow circuit of your carb is being used. I would try bumping up the pilot jet one size. if you can put on a head pipe then youll have no problem with a pilot jet.

[brettg]

thanks ill let you know how it works out