My neighbor gave me two 87 polaris trail boss 250 2x4 atv's. They have both been sitting for at least 3 yrs. I am only working on one at time. Right now I have the one I am working on running, But when you rev the motor it takes a long time to idle back down and when you put it in gear it seems to have plenty of power but after about half throttle it boggs down and losses power and back fires. Its kinda like the main jet isnt kicking in. I have taken the carburator off and cleaned it thoroughly with a little wire and compressed air, check the float and jetting. It has a new spark plug as well. I took the stator cover off and the fly wheel and found one of the magnets had broke on the fly wheel. It does not have a hard time starting and idles fine. Could this be the crank shaft seals or worn carb parts ? just looking for Ideas.

 

Not idling down on a 2 stroke could be an air leak, try spraying carb cleaner around the intake and see if the idle changes. The broken magnet is not good, probably the charging circuit, or it would not run if the ignition coil magnet was broken. Hopefully OPT (Old Polaris Tech) will get wind of this post and be able to help you out more. Whenever a quad sits for that long, seems a lot of gremlins take up residence and give you all sorts of problems until you "evict" them all !!

 

Sitting for 3 years is bad on crank seals,they usually sit with a crank full of gas and deteriorate or dry up and crack. Either way can cause air leaks,plus do as mentioned spray carb cleaner all around engine and listen for changes in way the engine runs.I'd replace the seals before it runs too lean and causes piston/bearing damage. Flywheel magnets were bad on the older models about separating and tearing up stators. A new flywheel is around 300 bucks. OPT

 

Thank you guys for the tips, I really appreciate it. I do what you recomended and see what happens. Also, I would like your opinion is it worth fixing these atv's up or am I going to have more problems then they are worth ? I have a couple of friends that think I should just go buy a new one.

 

A lot of parts are NLA as far as plastic,etc,but if you just do the basics to see if they run ok,crank seals,carb rebuild,etc then you should have a pretty good idea how far you want to go with it. If you just want something to putt around on,could be ok but if you're trying to resell a 25 year old atv,it wont bring much and you can put way more in it than you could ever get out. Good luck with the project. OPT