Has anybody had experience with WSM pistons? I just picked up a 97 Scrambler 400 that is in need of assembly. The guy had the cylinder freshly honed and included a WSM platimum piston with the engine. Is this piston better than the stock piston, or should I spring for the Wiseco piston? Thanks!

 

Learning what I have about the polaris models I would stick to a wiseco piston. They cost more money but they are a lot tougher. With a cast piston you are just basically waiting for it to break. If it is bone stock and the clearances are correct then it will live awhile. If he just had the cylinder honed without boring then you are probably going to be .001-.002 bigger than limit anyway, not to mention if the cylinder had wear. Have the jug and piston mic'd to check it all out first. You might find out that it needs boring to the next size.

 

not many have tried that piston becuase like bubba said its basically the same as stock. there was one other guy on here that did and was not happy.

 

thanks guys-
I finally got around to looking at the engine parts closer, and I found out the standard bore WSM piston is way too small for the cylinder bore! How do I figure out how much the cylinder has been bored and what size overbore piston I need to get? Thanks.

 

STD = 3.268" or 83mm
10+ = 3.278" or 83.25mm
20+ = 3.287" or 83.5mm
30+ = 3.297" or 83.75mm
40+ = 3.307" or 84mm
50+ = 3.317" or 84.25mm
60+ = 3.327" or 84.5mm
80+ = 3.347" or 85mm


Rick Ritter

 

Thanks Rick

 

Well, I measured the cylinder with a dial caliper, which is all I had, and it came out to be 3.38"! What the hell is going on with this cylinder!?! Apparently I'm in the market for a new cylinder since this one is bored more than I want...or do they make pistons that are .120" overbore?

 

hey three things did you buy that scrambler off ebay was looking at one on there sounds identical any way i have awsm in my wives 250 trail boss it is the teflon coated one have about 5 years on it no problems works great. also hpd sells a piston for the 120 over it is in there big bores but will run hotter had my 400 that high then resleeved it hpd site is hpd-inc.com hope this helps

 

Scramin-
Yes, I did find the ATV on eBay. The high bidder was a non-payer, so I received a 2nd chance offer of $1200. I offered the guy $1000 cash and we settled on $1050 cash. I'm a little bitter on the deal since I have run into this cylinder issue, and there are MANY nuts and bolts missing when he told me there might be a couple missing. Oh well, at least I'll be able to build this ATV to my standards and with the equipment I want it to have.