hey guys, i am new here and have been been trying to figure this out for about 3 weeks now.

I have a 04 KFX400 it has spark and compression but when i turn it over it takes a lil bit to start it up, then after it is started it will backfire then die after about 10 seconds. I need help becuase i am clueless. Anything will help at this point.Thanks!!

 

How is the fuel flow? Tried fresh gas? I believe those have a prime position on the petcock, is that set properly?

 

I have cleaned the the petcock and there was sand covering the filter. I cleaned that out and poured new gas in. Then clean then carb. But it still backfires and only runs for a few seconds.

 

Backfiring is generally a sign of being to lean. I would still think you may have a fuel flow problem somewhere. How is the air filter btw?