I bought this sportsman back in 2008. It has always given me problems with top speed. Started after I almost completely submerged it in the frigid waters of Jim Creek Alaska. I've checked spark plug...seems fine, it used to "hunt" meaning I could throttle it all the way and it would all of a sudden kick in to turbo, now it just wont go over 40 mph period. The throttle sounds like it wants to kick in but it never does. How do I get my go fast back?! What can I do? I not a master mechanic by any means but I do know my way around a wrench. Please help, my wife is killing me on her 500 and I just can't let it go on any longer.

 

kinda sounds like something in the ECM

 

Could be a number of things but start with the easier stuff first. First I suggest getting a popo repair manual(usually can get them reasonable on ebay) if you don't already have one. Will help greatly with specs/troubleshooting. I would take a look at the belt first. If you got some water in there it may have done some damage to it which will limit top speed. Do you run it in high a lot? Keeping it in low when under 15-20mph and whenever pulling/playing in the slop will save a lot on belt wear. Take a look at the air filter as may have gotten some crap in there(box may look sealed but I have seen them full of mud/water). Other thing to check is cable play-been a lot of threads here on that. ECM may need remapping but that can get pricey and would hit everything else before having to go down that road. Is it in deeper water a lot? One suggestion I have followed from others on here is taking the time to put dielectric grease in every electrical connection you can find.

 

is the engine reving up high but just don't have any speed? as mentioned check the clutch housing for belt and clucth issues.