2 winters ago we had to rebuild the top end on my trail blazer because it lost compression...were gonna end up having to do it again here soon and i was wondering if anyone knew why this happens and if theres a way to avoid it
thanks

 

the pleasure of owning a 2-stroke...

 

2 strokes will wear faster than 4 stokes it's just a fact of life. now if you ride a lot you will have to rebuild your top end after time. it also depends on how hard your ride. if give it a lot of high RPM"S all the time well, it will wear out faster.

 

Running synthetic oil If your not already will help extend life a little.
Other than that it's a 2 stroke thing they wear faster.


Jeff

 

i would check for a cylinder shape and sleeves,if the jug clearances after time is too loose you might to consider a boring over pistons to
still maintain good reliability,fresh iron make rings to seal better,stay with polaris pistons if top end rebuilt is a problem also.

 

There could be many, many causes for the compression loss. Here are some of my thoughts, and questions.

Was the first rebuild needed because of wear? If so, what kind of air cleaner do you use? Do you oil it like you should? Service it regularly? Are there any holes in it? Do you grease your carb boots?
Were the rings stuck in the lands? If so, what kind of oil do you use? Ratio? Was the piston scuffed?
Was the bore worn? Lots of clearence?
Was the machine work done by a reputable shop? Were the clearences checked before assembly?
Was the cases and crank seals pressure checked?
Was the mixture set correct?
Was a leakdown done to see what shape the rings were in?

All of these things and more can cause engine wear. Some can cause EXTREEM engine wear in a short time!!!! Or you may just put a zillion hours on it in a year and it may be just normal wear?

 

If everything is alright with it then i would say that it is a warm up issue if you are riding it in the winter....let it idle for 15 min....severe wear on pistons and rings can result or a cracked head....just my idea if everything else seems to be ok....if you ride it decent it should last several thousand miles without wear....