ive got a sportsman 500 2001. the other day i went to ride and the engine didnt sound right and lacked power. top speed was only 30 mph. ive checked the spark plug and replaced it. it acts like a vacum leak but i cant find one any help would be apreciated.

 

thats odd... sorry i cant help.. burnt belt maybe.. i aint sure what a burnt belt really does.. but i think they make it slower and more sluggish.. but i dunno about that sluggish!

 

We need more details, what does it sound like? When, hot cold always? What colour is your plug? Have you done a compression test, if so what was it, wet & dry? That's enough to get us going.

 

thanx anyway hozed. i know it aint the belt. ive got plenty of low end power. its the mid and top end that im having problems with.

 

the compresions fine. i put a new plug in didnt help. got good spark. it just acts like a vaccum leak. engine temp doesnt matter. it does hav a little backfire when you rev it in nuetral. hope this helps. thanx

 

Usually when it backfires it is due to a lean mixture. Run it in the higher rpm range and check the colour of the spark plug. If it's white it is very lean, grey is lean rusty brown is what you're looking for. If it is lean check the carb boot for holes or loose clamps. Check the air box cover for a good seal, a bad leak will cause the same symptoms. The 500 will not run without an airbox lid unless major rejetting is done.

 

I know it sounds dumb, but check your air filter. I've actually seen air filters so dirty, that the machine runs rich and floods out at 1/2 throttle. You can also have rich backfires...so it's hard to tell. If you have never changed your jetting, check the air filter. Maybe you have and just didn't mention it, but look at it, clean it, replace it, whatever..and see what happens!

 

<FONT face=Verdana size=1>pudljumpr, that is an excelent point, I have seen that too.</FONT>

 

I dont know if i am right but, This sounds like a worn cam to me... A friend of mind had a problem like this turned out the cam was junk.. It would backfire and had little or no mid and top end... Polaris has been known to have some bad cams... Pull the rocker cover and take a look while your at it check your valve clerance as well...