I drowned my Xplorer the other night, and when flushing the crankcase through the intake, I inspected the piston as best as I could. It is a standard wiseco piston, and I noticed a little wear on the edge of the skirt. I believe this wear indicates a little too much clearance between piston and cylinder, and this would explain what I consider to be excessive piston rattle. Anyway, I called Rick with RCR, and he is going to get me a .20 over piston coated by Swaintech, and I believe he said he would get a couple more coated for .20 over, and a .40 over along with a .60 over coated as well. These additional pistons he's getting coated are to keep in stock for us users. Just thought I'd let y'all know. Mike Chero was the first I noticed that referred Swaintech coatings, and you can do a search through the Polaris forum for more information on the coatings and Swaintech's website address. Again, this is just a heads up.

Waylan

 

walexa,

Thank goodness for those soft Wiseco pistons! If that were a stock cast piston, you'd probably be replacing a lot more than the piston and getting a rebore. This last summer I saw first hand what a broken cast piston will do to a two stroke motor. It wasn't pretty! The motor was out of a CR 125R dirtbike and a piece of the piston (with the crankshaft's help) managed to put a nice sized hole in the botton of the case, underneath the crank.

Swaintech is the only way to go as far as piston coatings go. If you are seriously into modifing you engine, or for that matter want a little insurance on a re-bore, get the piston coated. Swaintech coated some guy's pistons on his drag sled and they were routinely running EGT temps of over 1400 degrees and sometimes aproaching 1500. Normal uncoated forged pistons start to melt at 1350 degrees

The Poly-Moly coating on the sides virtually eliminates cold seizures and the ceramic coating on the piston dome prevents melt down. Granted there will be some cases where you have a cold seizure or meltdown, but you would REALLY have to work at it.

 

Mike,

Thanks for the response. I don't really think drowning the bike damaged anything. What happened was I was forging my way through a culvert that had about 2' of mud with about 1' of water on top........I was making headway so slowly that when then bike stopped moving, I just dug myself down real deep. Water entered the exhaust for the belt housing. In waiting for another buddy to get unstuck to come to the other side to pull me out, I shut off my motor. Water entered the muffler then and got on top of the piston and prevented me from cranking it. Once I got pulled out, I just removed the spark plug and turned the engine over to get rid of the water on top of the piston, and removed the drain plug from the bottom of the carb to empty water out of there. Got it cranked, and she ran fine. The next afternoon, I flushed out the crankcase to remove any water droplets that might have managed to stay in there, and that's when I inspected the piston.........I noticed no damage, other than very light scuffing on the bottom edge of the skirt. My engine has had what sounds like piston rattle since soon after I went to the wiseco. I didn't mic the bore or piston, just simply dropped in a standard wiseco in place of the cast stock piston as preventative maintenance. I believe the clearance was too great basically from the factory for the wiseco, since I had very few hours on the bike. Seeing the scuffing on the bottom edge of the piston confirmed to me that the rattling noise I've been hearing for some time now wasn't just a normal polaris engine noise.........rather it indicated the clearance problem.

Sometime back, a polaris dealer/mechanic told me that in several cases he'd seen, if an oil-injected 2-stroke gets water in the engine, and is run without proper flushing, it never quite runs the same without a rebuild. His theory was that the oil injection doesn't replace the oil film on the cylinder quick enough......and this results in rapid engine wear. He said the cure for that would be premix.......and I've been running premix every since I changed over to the wiseco.

I'm really looking forward to rebuilding my bike this time with the Swaintech coating on the piston. I've read several places that wiseco's rattle, but I've also read that you haven't experienced that rattle yet with the coatings. I'm keeping my fingers crossed.

I've got a question for you........what do you think about the Hotseat Coolhead with a 12 to 1 compression ratio..........I think I've read in one of your replies that you have that on your bike. Please give me any/all pros and cons.

Thanks,

Waylan