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  1. #1

    99 seadoo Compression

    I have a 99 GTX RFI and i checked the compression at just cranking the motor over but not starting. I just let the starter crank it over. It read 90 pounds of compression. That sounds low but what do you guys think? It runs like that but ive been having problems. I positive the problems are charging wise but 90 just seems low. Please help! thanks


  2. #2
    make sure to double check with another gauge....or another ski.

  3. #3
    if it's truley 90 you are pooped out

  4. #4
    olds72's Avatar
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    Quote Originally Posted by maczilla23 View Post
    I have a 99 GTX RFI and i checked the compression at just cranking the motor over but not starting. I just let the starter crank it over. It read 90 pounds of compression. That sounds low but what do you guys think? It runs like that but ive been having problems. I positive the problems are charging wise but 90 just seems low. Please help! thanks
    Here is the same answer I put on pwctoday this morning;

    I believe the factory compression to be 155 lbs in each cylinder. As I told you in a PM, your ski will not run correctly with the compression numbers you are posting. Make sure you are using a good compression gauge and retest. Aside from your charging issues (wich could be related to low compression) you are going to need to rebuild the engine. I don't know how your mechanic skills are, but this is a lot more than changing the oil in a car. You will definately have to read the manual and follow the steps outlined in it. First things I would do is pull the head and inspect the cylinders. Thats nothing more that a few bolts. Look for scaring in each cylinder. If they look good you may need only a topend job. Rebulding these engines aren't hard, but you definately need some skills and the correct tools. My tool bax deffinately got bigger after I started working on my ski. Believe me it gets involved, i.e. torque specs, leak down testing, engine allignment....

    When I bought my ski It had a bad engine. So I paid what I thought was a reasonable price for it and repaired it. I hope you did the same. So you have some choices to make.
    1. sell it as is and recover some of your money
    2. rebuild it yourself
    3. take it somewhere and have it rebuilt.
    4. buy a new engine and install it.
    5. part it out

    Good Luck!!

  5. #5
    Quote Originally Posted by olds72 View Post
    Here is the same answer I put on pwctoday this morning;

    I believe the factory compression to be 155 lbs in each cylinder. As I told you in a PM, your ski will not run correctly with the compression numbers you are posting. Make sure you are using a good compression gauge and retest. Aside from your charging issues (wich could be related to low compression) you are going to need to rebuild the engine. I don't know how your mechanic skills are, but this is a lot more than changing the oil in a car. You will definately have to read the manual and follow the steps outlined in it. First things I would do is pull the head and inspect the cylinders. Thats nothing more that a few bolts. Look for scaring in each cylinder. If they look good you may need only a topend job. Rebulding these engines aren't hard, but you definately need some skills and the correct tools. My tool bax deffinately got bigger after I started working on my ski. Believe me it gets involved, i.e. torque specs, leak down testing, engine allignment....

    When I bought my ski It had a bad engine. So I paid what I thought was a reasonable price for it and repaired it. I hope you did the same. So you have some choices to make.
    1. sell it as is and recover some of your money
    2. rebuild it yourself
    3. take it somewhere and have it rebuilt.
    4. buy a new engine and install it.
    5. part it out

    Good Luck!!
    Im gonna buy a new gauge and try the compression test again. I didnt press the throttle in at all. So maybe that wll make a difference. After that depending on what she reads ill decide what i want to do. Thanks!

  6. #6
    olds72's Avatar
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    you don't hit the throttle when doing a compression test. All your doing is turning the engine over by hiting the start button. The gauge reads the compression in the cylinder it is connected to. The engine should not start all.

  7. #7
    Quote Originally Posted by olds72 View Post
    you don't hit the throttle when doing a compression test. All your doing is turning the engine over by hiting the start button. The gauge reads the compression in the cylinder it is connected to. The engine should not start all.
    Oh all the replies on got on the threads on this subject people were saying the manual says to hold the throttle down while turning the motor over.

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