<div class="FTQUOTE"><begin quote>Originally posted by: embler

well, got a new battery for it now and I also did a compression check. I got 80 when cold and 78 when it was warmed up some. is that good or bad? if its bad, then anything I can do to bring up the compression without a fresh top end? I'm thinking the oil filter is clogged so I'm gonna pull it and see. maybe its not getting enough oil. the new plug I put in only has maybe an hour on it and its already carbon fouled. what's causing this? one other thing, when it dies, I can crank it over with the starter and it takes a while to start. but if I turn it over with the starter for a few seconds, and the use the pull cord, it'll fire right up! wth? help!!!!</end quote></div>

Oh man, that's really low! Time for a rebuild! I'm gonna venture a guess that the stock piston skirt let go. The symptoms you describe are exactly the same as what I experienced before.

 

Yep, it's rebuild time.

 

that sucks. it'll run fine when it does crank up and has plenty of power. will it do this when its time for a rebuild? I've never messed with 2 strokes only car engines. I'm assuming I did the compression check right. I whut off the fuel, hooked up my gauge, opened up the throttle all the way and then turned it over. is this right on a 2 stroke?

 

<div class="FTQUOTE"><begin quote>Originally posted by: embler
I'm assuming I did the compression check right. I whut off the fuel, hooked up my gauge, opened up the throttle all the way and then turned it over. is this right on a 2 stroke?</end quote></div>

Yup, you did it right. Stock polaris 2-stroke pistons are known for grenading. It's not that much $$$ for a top-end rebuild (including a bore job).

 

man, my uncle isnt going to like the news i've got for him, lol. he has still been riding it and he will probably ride it until it totally gives up on him. why does it start right up after sitting all night? i'm still learning on these motors as all i've ever really worked on before was my mustangs. what all needs to be replaced on the top end? im assumming the rings and piston. anythin else? should he just go ahead and get performance parts?

 

Typical bore should cost about 75 bucks. Depending on whether the rod is still good, should be about another 80-100 for piston and gasket set.

Not hard to do it yourself if you handy with a wrench.

Probably looking around 400-500 for a shop to do it all for you.

That's just assuming it only needs the top end bored and rebuilt.

 

Sledpartsguy on ebay has great prices on Wiseco forged piston kits (includes piston, rings and retainer clips). You might as well replace the wrist pin bearing too while you're in there. Take it to your machine shop and have them bore the cylinder to the next usable size (if the cylinder wall is gouged from the piston grenading, you may have to go several sizes over-bore, but not a big deal).

http://stores.ebay.com/Sledpar...QQsspagenameZL2QQtZkm


Stock 250cc bore size is 72mm. Over-bore sizes are 72.50, 73.00, 73.50 and 74.00. You'll need to know what size the cylinder will "clean up" at before you can order the piston kit.

 

Best to buy the piston from who ever does the bore job.But Do get the gaskets and piston pin bearing from sledpartsguy.

 

<div class="FTQUOTE"><begin quote>Originally posted by: ftwflh

Best to buy the piston from who ever does the bore job.But Do get the gaskets and piston pin bearing from sledpartsguy.</end quote></div>

Or at least find out what the bore will be, and buy the piston. Don't have the bore done until they have the actual piston at the shop.

 

thanks for the help guys. I told my uncle what's going on so its up to him to decide what to do. now here's the kicker. I took out the airbox and carb and completely cleaned them out, drained out the carb and made sure the vent lines weren't clogged or anything. I also replaced the oil and fuel filters. don't know if the spark arrester has ever been blown out so I take off the nut and at first nothing comes out, not even the exhaust while it was running. I killed it and tap all around the muffler with a mallet and still nothing. I took a screwdriver and poked in the hole. there was some blockage but if felt like some cotton material of sorts. are these mufflers packed with fiberglass? I moved it out of the way of the hole and started it back up. some stuff came out but not much. now the exhaust is louder and it seems to make a little more power. could the muffler be stopped up causing the low compression? reason I ask is because after I did all this I put my gauge back on it and now its up to 92. what's going on with this thing?