KFX 400 2005
 

Has anyone had trouble with this bike backfiring and hard to start? I recently had new piston, rings and valves put, machine is stock in that regard. I race in the atvccs cross country series in Tx and it's not good if your machine won't start on the line or dies during the race. I original took it in for not starting and that's what was replaced. The bike will start right away if I pull it only a few feet but then continues to be hard to start on the trail if it dies during the race. Does anyone have any ideas?

KFX 400 2005
 

check your valve clearance, maybe they arent in spec?

KFX 400 2005
 

thanks dvxdude for the note, I took it back to the dealer last sat., couldn't put up with it not starting and the backfiring just isn't right, I got a race this coming weekend, hope it our by then or I'll be a watching instead of racing, that won't make me very happy, I was the state champ in texas in my class last two years running, lucky I guess I haven't killed myself yet

I'll let you know what they say about it next week

KFX 400 2005
 

mine did the same thing. my problem was a faulty rev box.

KFX 400 2005
 

Mine does this if it is getting too much air flow....IE: the air box cover is removed... Of course you can re-jet it to fix this issue.

KFX 400 2005
 

i would have said air leak or rev box. my carb came out of the boot 1 time and it would start and when you reved it would back fire and die. ive had a cdi go bad and been riding die on me and hard to get started again. let us know.. good luck !!!

KFX 400 2005
 

sounds lean