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  1. #1
    Dryden, Ontario

    Default Wiseco Pistons SLT 700

    I picked up a SLT 700. Cheap! No compression. I didn't really have alot of time to tear it totally down so I did a top end rebuild and oversized the cylinders to 82mm (somebody oversized it before me). Installed wiseco's and finally found that the connecting rod lower bearing was letting go. Particles were coming through the transfer ports and causing debris to smash the top of the piston on the PTO. So I tore it right down and bought a WSM rebuild kit for the crank. Now I have a rebuilt crank and put a newer set of cylinders on and bored them out to 81.5 mm with WISCO's again. (.005" clearance). Reinstalled the engine. All fresh now. Took it for a few rides and it was running fine. Then, you got too wonder. On the way back from my buddies house. She shut down, then fired up again and ran on two. Then it stalled again, and still fire up. Drove it home. Put it up on the lift and checked compression. 30 PSI on the MAG side. Another melted wiseco. New crank and bored to spec. with all new seals. What is with this thing. I am starting to wonder if you install these what kind of trouble you will have? From my research, they need a real precious break in period due to the fact that they are forged and not cast pistons. Also, they need to be warmed up properly before you take off from the boat launch. They expand quickly giving you a cold seizure situation. I have another Wiseco on order to put back in the hole but I hope this one will work fine with a proper break in and warm up. What are your experiences with WISECO's in Polaris Watercrafts?

  2. #2


    Good notes. I don't have any answers but appreciate you sharing .)

  3. #3
    1988 Kawaskai JS300SX, 1994 Polaris SL 650


    Weisco Man,

    Good Read.
    I have used Weisco Pistons and Kits etc. in Carbeurated Outboard Marine Applications for years and never had a problem. (Mostly OMC triple two strokes (loop-charged), short shaft, used for surface running props at higher RPM's.)
    I appreciate that in these relative operating environments the engines and performance of the engines are at the mercy of many variables. Some beyond our control. Air temp, density, etc. Some in our control like, limitiations and ability to have proper continuity with water. These things we can manipulate, to better the longevity of our watercrafts.
    Loosing focus.?@*#
    Don't over look anything during-before-and after the build-up, even during first 10 - 15 hours. Cooling is critical, tie machine off and play with the squirt gun- the throttle. Feel the heads as best you can, with your fingers, during the warm up. Everytime! Feel the engine come up to temperature. Well maybe not every time after awhile.. Develop the feel for what your engine is doing. Be consistant.
    I know it all sounds intimate, but point I'm trying to make is never stop trying to understand what's going on even when it feels and still runs good.
    After all, I've often said: "High performance co-incides with High maintenance."
    Its all relative...good luck. Sounds to me like you know what your doing anyway, rather questioning the quality of the aftermarket engine product.



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