Low RPMS

Discussion in 'Outboard Maintenance' started by EER, Jan 2, 2012.

  1. EER

    EER I Love microskiff.com! Gen 2 Copperhead

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    What would be some reasons an outboard would't be turning enough RMPS at wide open to reach its proper range? My 09 Yamaha 50 2 stroke is only turning right at 3000 RMPS at wide open. I believe the range should be 4500/5500. Problem with outboard? Prop? or Both?
     
  2. topnative2

    topnative2 Well-Known Member

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    bad tach if u have the speed
    to much pitch if u do not
    boat to heavy
    was it running rt. before
     

  3. EER

    EER I Love microskiff.com! Gen 2 Copperhead

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    New G2 Ankona Copperhead, New Tach, No load on the boat, Motor seems to run fine. Don't know what kind speed its getting. But not performing (speed) as well as I thought it would.. Prop size is 10 3/8 X 13. I bought the outboard used and thats the prop that was on it. I expected to have to re prop the boat,so hopefully that will resolve the issue.
     
  4. topnative2

    topnative2 Well-Known Member

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    check your spark to all cylinders
    compression test?????
    prop sounds ok
    timing may not be advancing
     
  5. EER

    EER I Love microskiff.com! Gen 2 Copperhead

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    I wil have it checked. Thanks for the direction.
     
  6. Creek Runner

    Creek Runner Well-Known Member

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    1st start with a compression test all should be 110+ with-in 5psi of each. Next do a spark check which will more than likely will be fine. Next with the engine off move your control box lever to WOT and make sure the cable is opening up the butter flies on the carb all the way you can tell by the little bar on the side off the carb. The next step will be on the water, pull the carb cover, at WOT cover the throat of the carb with your hand one at a time and see if you get any RPM gain. When using your hand it will be a quick cover to just manually choke the engine. Another way would be to take a bright flash light and shine down the throat of the carb at WOT to check for fuel flow. Depending on what your diagnosis is on the following steps will tell you what system is failing and what needs to be fixed or if further testing is needed.