Posted by JaMeS_

i was going threw a feild and all the sudden it stop and i went over the handle bars i didn't think any thing of ti and got back on and it acted funny, so i went and found the rest of the group and i shut it off and i was a bitch to get it started agian and then it wouldn't run at anything under 4 thousand rpms it would drop a cylinder i still rode it for the rest of the day i got it back to the cabin and cleaned the carbs there was ice in them but it still ran like shit so when i got home i took it a part and on the PTO side the top ring was gone and it took a big chunk out of the piston and broke the top edge of the exaust valve hole in the cylinder.

 

so i over nighted new pistons and a cylinder. it a 2002 polaris 800 RMK so do any body got any idae why it did that

  

I run wiseco pistons in everything and you probably cold seized it. how cold was it that day and how long did you let it warm up? Wiseco pistons are one of the best pistons out there but YOU HAVE TO WARM THE SLED UP PROPERLY!!!! I cant stress that enough. If its not warmed up then it must have 10 min of idle time before you hit the gas and when you take off DONT wide open until you drive it for about 500-1000ft minimum wiseco pistons have a nick name siezco. Wiseco pistons are great just let the motor warm up. Cold seizing happens when the pistons heat up and expand faster than the cylinders so once you let it sit and cool down the motor may free up after sitting a while. I just rebuilt a motor for a kid with a 440 sno pro for the same reason. He let it warm up for maybe 3 min then wide open across the field he went and then it seized the end.

Posted by Klide

Posted by JaMeS_

i was going threw a feild and all the sudden it stop and i went over the handle bars i didn't think any thing of ti and got back on and it acted funny, so i went and found the rest of the group and i shut it off and i was a bitch to get it started agian and then it wouldn't run at anything under 4 thousand rpms it would drop a cylinder i still rode it for the rest of the day i got it back to the cabin and cleaned the carbs there was ice in them but it still ran like shit so when i got home i took it a part and on the PTO side the top ring was gone and it took a big chunk out of the piston and broke the top edge of the exaust valve hole in the cylinder.

 

so i over nighted new pistons and a cylinder. it a 2002 polaris 800 RMK so do any body got any idae why it did that

  

I run wiseco pistons in everything and you probably cold seized it. how cold was it that day and how long did you let it warm up? Wiseco pistons are one of the best pistons out there but YOU HAVE TO WARM THE SLED UP PROPERLY!!!! I cant stress that enough. If its not warmed up then it must have 10 min of idle time before you hit the gas and when you take off DONT wide open until you drive it for about 500-1000ft minimum wiseco pistons have a nick name siezco. Wiseco pistons are great just let the motor warm up. Cold seizing happens when the pistons heat up and expand faster than the cylinders so once you let it sit and cool down the motor may free up after sitting a while. I just rebuilt a motor for a kid with a 440 sno pro for the same reason. He let it warm up for maybe 3 min then wide open across the field he went and then it seized the end.

 

The other thing it could maybe be is 2 strokes are an odd motor. unlike 4 strokes 2 strokes momentarily suck in through the exhaust when the piston comes down so if a chunk of anything got into the exhaust ports it could potentially suck it back in and do some damage. My 600 ZRT broke a 2x2 piece of piston skirt off on the PTO side and it came up into the exhaust ports then got sucked into the motor again on top of the piston and smashed my spark plug, After that the chunk of broken piston melted and stuck to my exhaust pipe. I re gapped my plug and took off and it ran like new for about a mile then it acted as if it would miss sometimes and it would not hit its peak RPMs but sometimes it would run flawlessly witch was odd to me. The reason it ran like shit is because it was opening the exhaust port way way to soon because there was no longer a skirt to keep it closed. What made me confused is that it would run flawless a lot of the time.

its got exaust valves and they were fine, just finished putting the new pistons and a new cylinder on it runs much better

the same thing happed to me with my 03mxz 600 a was riddin and it died started it up and it ran like shit wouldnt go up much more than 4 grand tore it a part and there was half of the fucking piston gone took it to a deler ship and the ski-doo techs didnt even know what went  wrong    i     got wisco pistons in my race sled and havet had a problem (knock on wood)
[Edited by sledneck792 on 2/20/2008 at 6:29 PM]

mine just wouldn't run under 4 grand above that it was normal, my XCR has over 100 thousand miles on its wisco and the ones in my 800 only had 1,500 on them

ive always has trouble with wisco...they dont seem to want too keep running....u gotta let them warm up alot before taking off or its gonna fuck up.....also i heard this from a mechanic...he told me that wisco pistons are for preformance sleds that have to be rebuilt like every season....umm my segestion is to go back to oem....or go to some ceramic pistons....just my .2 cents but yea...

i put SPI T-MOLLY pistons in

Wiseco pistons are forged aluminum stock are cast , You can not run wiseco pistons in nicasl jugs there is not enough clearance in polaris application . wisco expand more than cast causeing what looks like cold ceasure . hope that helps

if you had ice in your carbs chances are you roasted a cylinder/piston beacuse of that, the passages in the carb got plugged due to the ice which  restricted the fuel flow and caused your cylinders to run lean. i can not tell you how many times i have seen this. the perminent fix for this is to use iso-heet (in the red bottle) found at your local auto parts store. one bottle treats 20 gallons gas, it removes water from fuel so your carbs dont ice up. (check your owners manual) they probably tell you to use this stuff. (((((((use iso-heet every time you fill up your tank))))))) also wiseco pistons typically need just the rings replaced after 2000-3000 mi. of use, that is what i  was told  by one of their tech's. which side did the piston break on? if it was the exhaust side this usually means that you have a lean fuel mixture, piston/cylinder scoring on the exhaust side is also from a lean fuel mixture

[Edited by prosxc on 11/11/2009 at 7:38 PM]