Looking for some help with a 2001 Sportsman 90. After about 10 minutes or less the engine backfires and then stalls shortly after. It will pretty much start right back up without issue maybe ride another 5-10 minutes and then stall again.
It does seem to smell hot. This happened on our last ride of the year last fall and again tonight after changing the spark plug. Last year I noticed inside the exhaust pipe it appeared to be cherry red. My thought is maybe too much carbon has blocked the flow...??? But would this be the cause of stalling and backfire? Any insight would be greatly appreciated.

Mike

 

it could be a cause of the problem but im not sure...now isnt the 90 a 2 stroke???or four

 

Sounds like the quads running on the LEAN side. Try to run the motor with the choke on and see if it gets better. Migth have an air leak somewhere and need to inspect all the intake parts for any cracks,tears, etc. That or do a leak down test on the entire motor.

 

how did the plug look that you took out? if its running too lean you will burn down the engine if you keep riding it that way. make sure the vent lines arent plugged and theres no water in the gas. if the pipe got red hot you defenitly are running way to lean for some reason.

 

THe plug looked fouled to me, black & slightly wet. The pipe was so hot last year that the pipe went from black & rusty to a whiteish color.

I did look at the air box and hose but I'll take a closer look. Last year at the begining of the season it was stalling but it seemed like it didn't take as long to stall. It was also obvious that the hose had come disconnected. I'll do closer inspection to see what I find.

Thanks guys,

Mike

 

could be that its loosing fire and then reigniting the gas to cause the back fire. if the plug is wet and black its not running lean.

 

Well I checked out the air box, lines etc... I changed the fuel filter and still had the same issue. For $85 our local Polaris dealer will diagnose the problem. So we'll see. I bought this machine used and haven't had to put any money into it. Hopefully they fix it and the problem goes away. Thanks for the help guys.

Mike