Well, live and learn, i found a "great" deal on ebay on a WSM Performance parts complete topend pistion kit 0.040" for a 400L engine. In the past i have always used Wiseco but a guy told me he had used this brand in a jet ski so , the price was good , i got it. After 3/4 of a tank of gas the exhaust side of the pistion skirt is in my pipe and lower case. Now i know why it felt like the mid range was acting funny. Luckly it did not hurt the cylinder - which i had just ported with the help and advice from Bubba. The bike ran great last saturday but last night at 1/4 throttle it locked up. Well i guess its time to sell my spare parts ( carb,4x4 drivetrain, etc.) so i can go buy a Wiseco pistion kit. What a fun day and yes i did a 1 hour break in on the engine.
later
hunt

 

Hunt,

Sorry to hear about that. I have often seen the WSM kits on ebay.........and have wondered about them. Hope your bottom end is ok.

 

I sent WSM an email and pictures of the piston and their reply: they said there was no history of having this type of problem with the piston- could have been dropped somewhere that would cause a hairline crack that could not be seen. They are sending me a new piston and ring set - FREE. From what i got they think it was just a bad or possible damaged piston. Well do you guys think i should put the new one in or get a Wiseco. Appeartly these pistons are widely used in jet ski engines. Give me your thoughts.
thanks
hunt

 

The wsm pistons appear to look just like stock, therefore, I would guess they are a cast piston. However, I've read somewhere that they are forged. If they are indeed forged, I believe the piston would be ok. However, I have taken used wiseco forged pistons and beat them with a hammer on the skirt without breaking the skirt off.........just for grins and to see how tough they are. If you have a used wiseco, and a used cast, try what I'm talking about. Try the used wsm piston. You should be able to tell if they are brittle or not. If it is brittle, I wouldn't put one in my engine.

Waylan

 

If it were me I would Ebay the WSM piston to get some of my cash back and go with a Wiesco.

 

I'm for that idea. Sell that WSM on e-bay and get something that wont break. I tore down my wife's quadracer a few weeks ago and the piston had 2 cracks in it. One was almost 1/2 inch long. A cast piston would have went south a long time before. I will always say that a forged piston is made for racing or hard riding.

 

Well, i ordered a Wiseco - have a race next saturday and am worried about the WSM being in my mod xplorer. Does anyone want to buy a piston?) Hey bubba, i could tell a difference with the porting and can't wait to see how it runs after i get another piston - thanks
later
hunt

 

No problem Hunt, let me know how it turns out,Bubba

 

I don't suppose you guys have the address for polaris do you? Thanks.

 

www.polarisindustries.com