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Thread: Yamaha 50hp Compression

  1. #21
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    Quote Originally Posted by SCmudder7071 View Post
    Checked throttle linkages to ensure all carbs are fully opening?

    Leakdown definitely.
    yes, make sure your carbs are synced
    I see so many boat motors where they aren't and owners don't realize it cause
    motor will still run good but you are not getting a full wot if not.
    I don't think this would cause your compression issue across all cylinders.
    That thing could run for years with the evenness they have across all three holes.
    I would take my camera scope and look inside the spark plug holes and look for scoring too

  2. #22
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    I know a guy who can make it roll out!

  3. #23
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    I know for a fact this motor has been decarbed every year....

    Moose, when you wanna sell it, lemme know.

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  4. #24
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    Eliminate the boat battery. Use jumper cables from your truck battery directly to the starter lug, and check the compression. Then if compression is not better, remove and clean the starter(may be gummed up). try it again. I have seen the actual starter wires have corrosion well past the lugs causing a bad connection and combined with gummed up starter it would not turn fast enough to even start. It was that way when I got that 115hp years ago.

    That motor runs to good to be low on compression.

  5. #25
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    Quote Originally Posted by Civil-Cock View Post
    Eliminate the boat battery. Use jumper cables from your truck battery directly to the starter lug, and check the compression. Then if compression is not better, remove and clean the starter(may be gummed up). try it again. I have seen the actual starter wires have corrosion well past the lugs causing a bad connection and combined with gummed up starter it would not turn fast enough to even start. It was that way when I got that 115hp years ago.

    That motor runs to good to be low on compression.
    Battery is fully charged, starter spins motor like a scalded dog, or appears to anyway.

  6. #26
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    are you in Columbia?

  7. #27
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    No I’m in Raleigh

  8. #28
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    Something wrong with your measurement. Your tester's either messed up or you're not sealing it to the head well. If it starts easily, idles good, and runs fine I wouldn't worry about it.

  9. #29
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    Yea I’d try a different gauge setup.

  10. #30
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    Update, got a different setup from the loan a tool at local parts store. 115 all three cylinders. That’s what I get for buying cheap ass Amazon compression tester I suppose.

  11. #31
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    Quote Originally Posted by scmoose View Post
    Update, got a different setup from the loan a tool at local parts store. 115 all three cylinders. That’s what I get for buying cheap ass Amazon compression tester I suppose.
    We still doing that carb job on the 8th?


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  12. #32
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    Overhaul it at the ramp

  13. #33
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    Awesome

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  14. #34
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    Quote Originally Posted by scmoose View Post
    Update, got a different setup from the loan a tool at local parts store. 115 all three cylinders. That’s what I get for buying cheap ass Amazon compression tester I suppose.
    I've had that happen before. But dang spending $250 on a Snap On compression gauge that I'll use every now and again.

    Hate that I'm gonna miss the festivities again this year.
    [SIGPIC][/SIGPIC]
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