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  1. #1
    Buaidh No Bas howestek's Avatar
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    What Caused This

    What caused this?
    Ski is a 1390 powervalve. I initially thought the powervalve dropped. Doesn't look that way though after breaking apart the powervalve assembly and gauging the valve travel in the cylinder. I pressure tested it before breaking it apart. It would drop about 0.5 psi from 9 psi in 20 minutes. 1 psi in 45 minutes to 1 hr. Could not find the source of any leak with soapy water until pressuring up to 10 psi. It was still a slow leak, but I could see it at the crank seal. Here's pics of #1, #2, and #3. Sorry for the pic quality.
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  2. #2
    "Hustler" Inkaddict's Avatar
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    Those leak down results dont seem that bad... 3 Is way lean though... What was your compression before it burnt down? Wash on 1 and 2 look good.. Does the head have any signs of deto?

  3. #3
    I agree the seals won't hold back infinite pressure I also do a vacuum test on mine because of the forces the intake cycle places on the seals

  4. #4
    Buaidh No Bas howestek's Avatar
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    Quote Originally Posted by Inkaddict View Post
    Those leak down results dont seem that bad... 3 Is way lean though... What was your compression before it burnt down? Wash on 1 and 2 look good.. Does the head have any signs of deto?
    I think the loss of compression (blowby) cleaned up #3? If I look very hard, I think I can barely make out a pistonwash that is less than the others shown. Compression was about 148-150-150 according to my innaccurate gauge. No signs of deto on the head. Just a little metal on the exhaust side from the piston/nik. No pitting.

  5. #5
    your right your pics suck! lol I can't tell if the pisty is carbon black or silver
    did just a section of the piston chip off? or is it a ring snag

  6. #6
    "Hustler" Inkaddict's Avatar
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    Quote Originally Posted by howestek View Post
    I think the loss of compression (blowby) cleaned up #3? If I look very hard, I think I can barely make out a pistonwash that is less than the others shown. Compression was about 148-150-150 according to my innaccurate gauge. No signs of deto on the head. Just a little metal on the exhaust side from the piston/nik. No pitting.
    How's the exhaust port look? If you look at the piston it kind of looks like the ring snagged the port Was the ski loosing rpms as you rode before it shut down.. I snagged a ring on my 04 and it looked very simular...

  7. #7
    Altezza01's Avatar
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    looks like your PV dropped and hit #3.

  8. #8
    Buaidh No Bas howestek's Avatar
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    Quote Originally Posted by ZMANN View Post
    your right your pics suck! lol I can't tell if the pisty is carbon black or silver
    did just a section of the piston chip off? or is it a ring snag
    This pic is mucho better. It is silver and cleaned off. Just a small section of the piston is chipped off. Rings are still there but ragged. Cylinder is scored on the exhaust side. Some solids damage on the top of the piston (picture looks worse than the naked eye)
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  9. #9
    Buaidh No Bas howestek's Avatar
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    Quote Originally Posted by Inkaddict View Post
    How's the exhaust port look? If you look at the piston it kind of looks like the ring snagged the port Was the ski loosing rpms as you rode before it shut down.. I snagged a ring on my 04 and it looked very simular...
    I was riding it about 15-20 minutes warming it up when the engine turned off. The day before, I had gutted the rear of the ski looking for a small leak and thought that I might have a bad connection from putting it back together. It started right back up and I feathered it for a while before hitting 7300 rpm real quick. No rpm problem then. I ran it easy for about another hour when I sucked something into the pump. After cleaning it out, I got up to about 40 mph before the engine stopped. It took a while before I could start it this time, and when I did, it was 300 rpm down. Back to the dock I went.

    I don't see any damage in the exhaust port itself, but there is a nick from the exhaust port moving upwards about an inch or two.

  10. #10
    Buaidh No Bas howestek's Avatar
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    Quote Originally Posted by Altezza01 View Post
    looks like your PV dropped and hit #3.
    Thats the first thing I thought when I pulled the head. However, the PV linkage and stop are perfect. I can't purposely make it drop far enough to have hit anything.

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