First I'd like to thank all for their input in the matter, has been very informative.
Now on the subject on oil as pointed out by Thor, My friends & I use premium 2-cycle outboard oil for watercooled engines. I'm not sure if it's labeled ISO-L-EGD, (need to go check after my morning coffee), but we never had any problems using the stuff. Are we making a big mistake on our choice of oil? This subject probably came up before but I',m kinda new to the forum and I'm enjoying this anyway.

 

In order to sleeve the cylinder, the cylinder is dipped in a hot tank and the sleeve is chilled. The sleeve is then pressed into the cylinder. Rumor has it that polaris then immediately bored the sleeve while it was still cold. This made the bore slightly larger when the cylinder was raised to room temperature (right at the edge of maximum running clearances). Then as the engine got broke in, the expansion caused by operating temperature made the piston to wall clearances even larger. This combined with the properties of pistons everyone else described caused the cracking of their skirts. I found a cracked skirt on my 350 when I removed my reed cage. After the first bore this problem is remedied.

 

TC-W3 Oils are good but are not the best for air cooled engines. (Outboards have an unlimited supply of coolant and operate in a very narrow temperature zone)

Please read this link regarding the history of two cycle lubricants

http://www.goa-northcoastoil.com/tips/2cycleol.html

 

http://www.spectro-oils.com/faqs.htm

You may also find this link to be of interest to you if you want to read more about two cycle oils and the TCW-III vs JASO vs ISO ratings. There is a lot of information down in the snowmobile section.

 

Thanks Thor for the links. I'll be more picky about my oil from now on. This is my first atv and I would like it to last as long as possible, and this is a good place to start.

 

yeah my buddy broke a piston then he got it rebuilt and the problem occured again and what it was caused by a timing slip due to a bad fly wheel.Hope this helps you.I dont have the same machine I have the 500 4 stroke and had no problems so far .