hey atv addicts, i'm a new atv owner and was wondering how hard would it be to rebuild the top end on a 91 trail boss 250. i found the four wheeler for 600 bucks. it quit on me right after i bought it, which the guy told me it would probly need it soon. took it to my polaris dealer and they quoted me 500$ plus the cost of the diagnosis. i found a wsm rebuild kit for it on ebay for 59$ it seems like it would be simple but time comsuming. any help you could give me would be greatly appreciated.

 

If you are mechanically inclined then you can do a top end rebuild on a 2 stroke in about 3-4 hrs. It is very easy. Get a rebuild kit and get the cylinder honed. You dont even need to take the engine out of the frame. You can do it while it is on the bike.

 

Yes, once you take off the pipe, intake stuff, head and base bolts, the cylinder will come right off. It really is easy. If you have a ring groove or unsure about the condition, have it checked before buying a piston so you can get the right one and bore it if needed. Attention to detail and some patience will yield you some good results.Bubba

 

thanks for your help guys. but has anyone seen or heard of the wsm rebuild kit. is it any good. there on ebay under polaris atv. im wondering if this is a complete kit. or if i should go with the wiesco kit? wiesco 175$ wsm 59$

 

WSM is a good brand. Not as good as wiseco but better than stock. You will be ok with that kit.

 

I have the WSM in myn and before that I had Wiseco and so far the WSM has outlasted the wiseco by 2 years, I lost compression like crazy with my Wiseco and my engine slapped and rang. It's quiet and smooth with the WSM. It's very easy to do a rebuild, you need patience, keep things clean don't get any dift in the engine, if you have a lot of dift on the engine now it might be a good idea to wash all of it off before the rebuild. When you are putting the top-end on be sure to get the rings lined up on the pins or you won't get anywhere, put a rag over the bottom end just incase you drop one of the clips. I can't think of anything else but break it in easy and you will have a long engine life and use good oil.

 

just got back from the dealer 510$ rebuild carb, top end (wiesco). i think its worth it with the warranty. or i could pay them 200 bucks for the diognosis bring home in a box do it my self hope like hell it works. what do you think

 

oh yea! they said they bore it to .050. does that sound right ???

 

If you have the money I'd let the dealer do it. I don't thing Wiseco has 0.050 over just even sizes like .020, .040 etc.

 

well the service guy said that they would be boring the cylinder 1 mm. he said that i .050. he also said that .020 is almost half a mm. i don't really care as long as i get some good long alone time with my atv.