300ex backfireing

[hondarider2006]

my friend has a '95 300ex and dear god does it back fire. He has a cobra exaust, k&n filter, and dyno jet kit. His plug is black, so he isn't running lean. But after running wide open for a little while, this thing will shoot 8 inch flames:eek: Can someone had us in the right direction on what to do? Thanks in advance

[BS300ex5]

how black? sounds rich as hell

[TeamC&GRacer]

you probally have the jetting way off. What main jet are you running in their right now? I just had the same problem with my 426ex. I was too lean at 150 so i tried a 165.. little bit rich but im going to a 162 which i think will be fine tuned to run perfect.

[jay's 300]

Also check the header gasket, you may need to replace it. Same thing happened to my buddy's 300 when he changed pipes. Put in a new gasket and took care of it. :D

[Ryan]

Sounds like your buddies main jet is way off. Definitly to rich.