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  1. #1

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    1990 Kawasaki 650 low compression

    Well my ski compression is at 90PSI per cylinder, ski still runs and amazingly well. Any suggestions or a good starting point, I was thinking about top end rebuild kit, resurfacing piston sleeves if they can be resurfaced not really sure to be honest. Would you say this is a legit kit http://www.ebay.com/itm/KAWASAKI-650-TS-SX-X2-JETMATE-JETSKI-JET-SKI-STAND-UP-TOP-END-REBUILD-PISTON-KIT-/180729975483?pt=Personal_Watercraft_Parts&vxp=mtr& hash=item2a145892bb#ht_1344wt_1270 ?


  2. #2
    steve45's Avatar
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    Before you order the kit, pull the head off and see if there is any damage to the cylinders or if they're already oversize.

    I've purchased several things from epcot21, he's a good seller, but the parts are not Kawasaki, they're aftermarket.

  3. #3
    john zigler's Avatar
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    if you show to have 90psi on each cyl, and your ski runs good, i am suspecting your compression gauge.

    your 650 would have had 150 psi originally. a drop in 60 psi is substantial. it would not run. not to mention, usually it
    is just one cyl that is very low. ( not that it could not be both).

    i would first, have your gauge checked, or try a different one.

    if you are still unsure, you can pull the head, to inspect, but a lot of times, you really cannot see anything,
    until you pull the cyl.

    if you do need, or want to rebuild, you can bore your cyl to the next sized larger pistons. we offer this service
    here if you need. i can also supply new pistons, rings, gaskets, etc.

  4. #4

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    Gauge is brand new which could be defective although very unlikely, but I'll try a different one this weekend.
    Thanks.

  5. #5
    john zigler's Avatar
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    Quote Originally Posted by GreaseMonkey View Post
    Gauge is brand new which could be defective although very unlikely, but I'll try a different one this weekend.
    Thanks.
    other things can give a low compression reading.

    make sure your battery is good. a bad battery, or a slow cranking starter will give lower numbers ( ski may still start & run, but cranks slower than normal).

    leave one spark plug in when doing the test. the compression in the other cyl actually HELPS with cranking.

    i really cannot see how your ski would run ( if at all) with truly only 90 psi compression.
    Last edited by john zigler; 02-03-2012 at 09:45 AM. Reason: spelling

  6. #6

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    I have already tried that, battery was fully charged, first time i had both plugs out and showed around 87PSI each second time I left one plugged and got 90PSI, still thinking that I may have faulty reading I re installed both plugs let the ski run for about 30 seconds and was still showing 90PSI

  7. #7
    steve45's Avatar
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    High elevation will lower compression numbers, but you'd have to be really high to drop it that much. Where are you located?

  8. #8

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    Well, John you were absolutely right, gauge was showing incorrect reading, I rented out another one from Autozone and 150PSI in each cylinder, what a relieve . Thanks a lot guys for all of your help.

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