Just brought mine in for the same problem. Mine is a Sportsman 500 HO 4.5. It was something very stupid. The carb is attached to the engine with a rubber boot or rad style hose. The thing got loose after a few back fires. When the engine was cold, it appears that the boot was making a half decent tight fit between the carb and the engine. When the engine got hot, the boot got soft and created too much of an air gap between the carb and engine. Therefore the engine stalled and booged down and could not be restarted before the whole thing cooled down (the rubber had to cool down and close the gap between the engine and the carb to a level where the air leak would be minimum).

Try this and I hope this is your problem.

 

So - what was the solution??? SGajan?

 

Any answers?

 

Dealer cleaned the carb, adjusted, checked cam (no significant lobe wear), new plug. Runs 100% about 90% of the time - when it's warmed up it still does it but at higher speeds...

 

I neighbor bought a '98 500 last week that idle great and would back fire at about 1/2 throttle and not run beyond that. After reading this, I told him to check his cam and sure enough the exhaust lobe was completely worn down. I'm surprised it would even idle very long. It has over 4000 miles on it. I know this forum has save him hours or work and a lot of money.

 

A friend of mine had the same peoblem

 

I have the same problem as mentioned above. My cam looks good. Im at a total loss.. Did any of you guys ever get your quads running? For those of you who replaced the cam, was that the answer to your problems? Please advise!!

 

My 2000 500 magnum is doing the same as rungunner and sgajan. Only mine will drive but only up to 20-25 km per hour. When give it gas to go faster it bogs down and backfires. Please guys let us know what you come up with.[img]i/expressions/face-icon-small-confused.gif[/img]

 

I realize this is an old post, however, this sounds to me like the same problem I am faced with . My 2000 500 magnum has the same symptoms.
Can anyone shed some light on the subject. Don.t want to pull the head off for nothing.
Any help would be appreciated..

 

Any advice here? I still cant get this quad going...