Recent content by 1up

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    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Thanks, yes indeed. Can confirm engine runs strong now after t-stat replacement and carbs being cleaned out. The kicker was the autolube-dispensing is either faulty or may need some time / air bleeding. Luckily premixed the fuel to be on the safe side. Thanks all for your help and wish...
  2. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    A new boating season and a new update. T-stat replaced, and carbs cleaned. Cyl #3 one was basically all clogged up. Cyl #2 was partly dirty. Hope to provide an update in a couple of weeks time with the boat in the water. At idle it goes fine now.
  3. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Today's session with the motor points to overheating. Could drive the motor for longer without it losing rpm and it is colder in the water and ambient temp too. Both screws to the thermostat housing broke so will drill them out and then replace t-stat. Will go through all carbs and clean them...
  4. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Fuel pump checked. It didn't let out any fuel through the port. Found the spring seat and got the pump back together. Next test for spark but the main battery switch is lost so ordered a new one Gotta luv it. :)
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    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Ok will check for that.
  6. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Interesting. I need to review that. Does that mean a vacuum line would go between the back of the pump and the crankcase? Not sure I saw such a hose.
  7. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Perhaps I overdid the check then. What does 'pulse port'refer to? I can see an 'In' and an 'Out' fuel connector on the pump housing where the fuel line comes from the fuel filter, the out side seem to feed the three carbs.
  8. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    So I got one hour at the boat dock today. I opened the fuel pump to check the condition of the membrane. I could not see any tears or issues with it. Granted, it seemed paper thin though, but appeared intact. Of course a spring from the bottom fell out and a shim. I captured the spring, the shim...
  9. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Thanks for the details. Will try some more with the engine.
  10. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Thanks for feedback. One look oily, one look like it never got spark, plug for bottom cylinder. I feel I need to verify spark, testing leads first. I was alone at the dock today. With a helper I can ground the spark plugs and check for spark. Perhaps as mentioned there are bigger issues. Still...
  11. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Howdy folks, after an evening messing with the engine and mosquitos here are the results: Compression test conducted below operating temp, about 130 PSI for each cylinder. Minor variations. Maybe the number would have bwen higher should I have kept the starter on for a bit longer. Spark plugs...
  12. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Thank you for the condensed write-up. Will update when there is news. It is a rainy week ahead locally but the idea is to get the engine sorted for late season fishing and cruising.
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    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    That is what it seems like too. We removed the fuel hose with connectors and bulb for further inspection / replacement yesterday.
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    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    All good tips to check off, thanks. Compression is not verified. Judging by the general condition of the engine I would think it is a relatively simple fault. It looks in good condition under the cowling and sounds right idling at what would be crusing RPM. Eventhough it was a very slow and...
  15. 1

    Yamaha 2-stroke 50HP 1980's bogs and not reaching max RPM

    Motor is from 1987, 50DEO 6H5 L
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