SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Mar 2005
    From
    Southern Illinois
    Posts
    28

    Default What did this piston try to eat??

    Well after driving 900 miles and 15 hours from Illinois to Tampa FL I got to ride for about 30 min. before my jetski threw in the towel. THis was actually the second time it seized on me, I didn't know why it died the itme before, but the conditions were the same. I had already been riding for about 20 min. close to the dock never being at WOT for more than a second or two. Then after riding at WOT for about 5-7 min it seized. After getting a tow from a budddy and getting it back home it started right up and ran great. Keep in mind that it had seized on me before and it would still run 65 mph after it seized the first time. Well after it did it again I knew something was up. I'm attaching som pics of the pistons. The mag cylinder is the one that seized the other two look about the same and are in pretty good shape. My question is what caused the failure?? Do I need to break it down more to check the crank?? I didn't find any debree in the bottom of the case and the bearings on the rod are in good shape. If there is any more pics that would be helpful let me know, one of the pics is of the center cylinder.
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  2. #2
    Joined
    Jun 2002
    From
    Charlotte NC
    Posts
    1,868

    Default Re: What did this piston try to eat??

    Looks like there are parts of the piston pin bearing or the pin that centers the rings on the piston. Look at the piston and see if both of the ring guides are still there. You had debris flying around the engine for some time by the looks of the piston and some of it must have been in the crank area. You may have crank bearing damage but you wont know for sure unless you take the entire engine apart.

    The piston looks like it failed from running lean or water ingestion from the dull grey and it seams to have been washed clean. It may be starving for fuel or has an air leak in the manifold gaskets or crank seals.
    Providing mobile JetSki service to the Charlotte / Lake Wylie area.

  3. #3
    Joined
    Feb 2005
    From
    Kansas
    Posts
    112

    Default Re: What did this piston try to eat??

    Looks exactly like a piston out of a 650 that I had to toss. Looks like pieces of a crank bearing failure due to water ingestion. Dank is exactly right...

  4. #4
    Joined
    Mar 2005
    From
    Southern Illinois
    Posts
    28

    Default Re: What did this piston try to eat??

    I think you guys are right. I pulled the engine last night, I haven't seperated the case yet, and found large peices of metal right by the reed valve in the mag cylinder. I also found a small puddle of what looked to be oil in the bottom of the crank case of the mag cylinder. I took the cover off the magneto and a small amount of oil ran out, Is that common?? It seems to me the cylinder was getting oil and fuel but then again I'm pretty new to this... Is it common to see a puddle in the bottom of the case? How do I determine if it was water of lack of oil? This might be a streach but is it possible that the carb was only lean at WOT? The only reason I ask is becasuse both times it seized was at WOT and I had already been riding for about 20 min.... On another note, I printed the engine removal guid off SBT, it was for a 1200 and I have the Virage TX but it said to remove the entire pump. I just took off the four bolts on the back of the pump, removed the nozzle, stator and impellor, and pulled the drive shaft out the back. This seemed to make more since because now I don't have to reseal the ride plate and pump houseing to the hull. Did I do something wrong here, or were the Polaris engineers really thinking?? Thanks for all your input so far.

  5. #5
    Joined
    Jun 2002
    From
    Charlotte NC
    Posts
    1,868

    Default Re: What did this piston try to eat??

    Yes it can be leen only at WOT. Anytime you rebuild and engine be sure to rebuild/clean/check the carbs.

    That is what they mean when they say pull the pump. I have also had luck with some Polaris ski's just unscrew the engine coupler and it will slide down the splines far enough to allow you to lift the engine. Saves a good 30min. doing an engine swap.
    Providing mobile JetSki service to the Charlotte / Lake Wylie area.

  6. #6
    Joined
    Mar 2005
    From
    Southern Illinois
    Posts
    28

    Default Re: What did this piston try to eat??

    Well I found the problem....Both front main bearings went out. When I took off the magneto some of the bearings litteraly fell out. It wore down the crank about 1/4 inch. The funny thing wasthe ski would still do about 65 mph. Looks like I'll be turning to SBT for a new engine and some carb rebuild kits.....I would be glad to hear any advice or tips while I have the thing apart.

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