1999 Artic Cat 500 ATV bogs down and backfires

[Bruce Madsen 0]

My 1999 Artic Cat 500 ATV has started bogging down and backfires shortly after starting.  Any suggestion for a remedy?

[Ajmboy 512]

Has it sat for a while or did it just start happening all of a sudden? When was the last time it ran fine? Did you do anything, tune up, part changes?

[Frank Angerano 837]

Agreed with @Ajmboy could be a foiled plug or a dirty carburetor as well as bad gas. 
 

[Bruce Madsen 0]

Gas is new, plug is new.  It first backfired in 3rd gear going about 15mph. I changed the plug right away, didn't help, the plug was quite black when I changed it.

It idles a little rough and when I try to rev it up it starts backfiring.  It had been running great all fall.

[Frank Angerano 837]

Only thing I can think of on the simple side would be a dirty carburetor or stuck choke, maybe poor fuel delivery from the tank. 

Second thing would be electrical. The spark could be breaking down so it could be a bad rectifier or ignition coil, maybe water inside the kill switch or ignition switch, a break in the wire harness maybe where you have an intermittent short. You can do some easy testing  on some of the electrical  parts other then the cdi. 
 

lastly I would check the timing to make sure it hasn’t jumped a tooth or two on the cam sprocket.  Based on the backfiring it’s a symptom of timing but hit the simple stuff first before you start digging deep.  

Honestly and I don’t want to sound repetitive we have had members here that swore the gas was fine and the plug was good and after a second look it turned out to be just that.  
Hopefully this helps you out. 
 

 

[mikeexplorer 231]

Valves that are out of tolerance is another issue with backfiring. Usually the ATV is hard starting as well.

 

Mike

 

[Bruce Madsen 0]

Suggestions for Carb rebuild worked great.  Up and running!!