Sorry gave you a link to carb parts. 98 Sportsman 500 pistons | eBay

 

Hi there! I'm brand new to the forum as a result of a immediate power loss to my 01 Sportsman 500. It has 1770 miles, never had problem with it. It happened after riding it slowly up a shallow creek (not above the foot pegs and also in the snow) had a plenty of power loading back into the truck.) Unloaded it and within minutes lost significant power. (I do all my own mechanical work but not professionally trained) Sounds like a V8 running on 5 cylinders.
What I've checked/done: Clean fuel & filter, air filter was clean, carb & jets were clean, diaphragm moves up with throttle increase, set valves @ .006, disconnected limiter plug, doesn't seem to be starving for fuel or air. Compression is 80 psi. does NOT backfire. Runs rough in neutral and won't build RPM's. Have not checked the cam exhaust lobe as I didn't know about that problem before last night. Didn't know if that could happen suddenly like mine seemed to. Limited knowledge on Polaris's here so I know there's likely other causes I don't know about. Your thoughts would be greatly appreciated! Thanks! stan

 

Pull the recoil cover and see if there is any water or corrosion on the pickup coil or stator.Clean the area up with contact spray cleaner. 2001 has the HO cam and not normally a problem like the older cams were.Not a bad idea to pop the front panel and clean the electrical connectors and use some electrical grease.Next area would be the belt and clutches. Water may have enter and causing the problem. You can clean the clutches in an open area with an air nozzle. If the belt is stretched,cracked or glazed,replace it.Might be a good time to have the clutches looked at also.

 

Hi there!

Did all you said on the stator side, a little rust in there but no moisture. Cleaned it all up. Started it back up without the air cleaner on and noticed fuel blowback, so wondered again about the cam, looked at the plate and noticed it is a 1999. (I bought if from a friend who inherited it) took the cover off and cranked it over, significant difference between the lift of the intake/exhaust so I checked the lobe. Pretty much worn off. Sound about right with how it's running? Any cam brands to stay away from? Also, I'll plan on new valve seals, anything else? Trying to keep the cost low but want to do it right.
Can't believe it wore out after 1700 miles. I did a head job on a Bombardier and top end on a Quad last summer, so I'm pretty confident, but feel free to give my any advice you deem necessary. I hate doing things twice

thanks again for your help! -Stan

 

Bummer on the year model and cam.. Plenty of replacement cams on ebay. Always replace the exhaust rocker arm also. Niche in their adds sound good,but several others you can look at. You can just get the cam and rocker or replace the intake rocker arms in a kit also. Look through these.polaris sportsman 500 camshaft | eBay
Only difference between the old cam(other than being soft) and the HO cam was the duration. Lobe height was the same.

 

Great!

Thanks again!

 

I’ve had a similar problem with mine for the last couple of years, tried this and tried that. The backfiring thing was simple air flow problem. The air intake that goes up by the gas tank was not seated in the right spot and was sucking up to the plastic, basically staving it of air. Nd getting horrible fuel mileage.You guys might want to check that as a solution. But fixing that only made the boggling down issue worse! Had no power at 3/4 to wide open throttle. Found the black diaphragm part would stick and not slide up when on the gas. Basically floodingit out when you wanted power the most. If when you completely clean it and it still won’t work properly, then it’s time for a new carburetor. Now after fighting it for 3 years, mine is finally working properly. Good Luck out there. Hope this helps.

 

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take off the intake tube that bolts to the top of the airbox lid and block that whole off about three-quarters of it with your hand and rev it up Bet you it revs up perfect I just did a bike that had the same issues and when I blocked 3/4 of that hole off out revs great .....

 

Holy crap that's alot of replies, I simply can't read them all. Cam if it hasn't been done. And here's a silly one. My neighbor faught with his, turns out he sucked in the piece of foam thats suppose to go around the air box lid/ spout. It was jammed in there. I've also seem people pinch them under the plastic between the tank if it doesn't come out with the air box lid/ spout,

 

I noticed that mine will rev up and run perfect if I restrict the air. Does this mean to much air or not enough fuel?