im having the same problem, ive replaced clutch, belt, needle and seat, air filter, spark plug, cleaned the carb, i took the carb off and used rtv to get a better seal against the engine, rtv'd the entire air intake so that it is air tight etc etc... i have gas still coming out the bottom of the carb, gas spraying into the intake from the carb when i give it throttle, boggs down backfires through carb. the exaust cam has been my suspect as of late when i pulled off the cover like was said in the previos post the rocker arms move slightly and the cam moves less it is exhibiting all the symptoms of the exaust cam being worn so thats my last try before i hand it over to the dealer.

 

There is a service bullitin that was put out on these late 90 model sportsmans about the air filter sucking to tank. My buddy had a 335 would run great then he would get on it and wouldnt throttle more than halfway and bog out it may appear to be off the tank but can while riding it actually move and suck to the tank the service guy at the polaris dealer here showed him how to cut the tube so it wouldnt suck to the tank. It may not be the problem but its worth a try.

 

you also gotta watch out for the foam around your gas tank slipping down and covering up the intake.

 

hey yall, just wanted to say thanks for all the postings about the Sportsman 500 - just bought one with the exact same problems as described in the last 11 pages. We suspected the cam and you all confirmed it - same symptoms. If lobe is worn will be looking for a non-plaris part...any suggestions on a reasonable priced aftermarket cam and exhaust rocker? Thanks again (I love the WWW).

 

ive been searching the net for days now for a aftermarket cam but havnt found anything. its looking like the only option is oem, which gos for about 250.

 

Hello, i had a similar problem with a Trailblazer 250. I took apart the carb, cleaned the main jet and pilot jet, then moved the jet needle down one notch.It runs like a champ now. I did have to also adjust the throttle freeplay. Good luck

 

Might help...
Put the atv in a dark place and check for spark plug wire failure.
I replaced the bad wire and fixed all problems.

 

Have same problem with both of my 500 scramblers. Both will idle all day. One has black plug and smokes. Think the timing is off. Other one just recently hapened. Going to check everything i read in this forum. Hoping its just valve clearence or somthing simple. Tearing into both of them tomorrow. Will update.

 

Not sure what these guys sell the Cam for can,t hurt to ask. Aaen Performance - Polaris ATV 500

These Guys sell the OEM for $260 Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

The worn Cam was a pre 2001 thing. All replacement cams are now the High duration H.O cam now on any 500,425,455, even for the pre H.O sportsmans.

 

I found a place on ebay the price is 250 usd and has lifetime warranty cycles r us are the selers also can find them on line it wears out they replace that price is with exhaust roker arm included