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max rpm power curve

in 2 Stroke Technical Questions 6 years ago
My 503 DCDI is running really well at all speeds, but the maximum rpm is 6000. It reaches that at about 2/3 throttle (slides about 3/4 open). More throttle has no effect. I've tried adjusting nearly all of the pitch out of the Ivoprop and static rpm still never goes over 6000. Dialing in quite a bit more pitch brings static rpm down to 5900 but that still comes at 2/3 throttle. I'd like to get to the max power of the engine at 6800 or at least at 6500. Any suggestions?

  • Re: max rpm power curve

    by » 6 years ago

    Sounds like you have to much pitch...Should aim for around 6250rpm static secured on the ground.

    At the moment its like trying to drive a car uphill in to high a gear.

    Is the prop the correct one for the a/c and the correct dia...if you cant lessen the pitch maybe a bit off the dia...prob seek further help before you do that...I'm not expert.

    Only other thing I could think of it the engine is down on power..low compression maybe...has it ever reached full RPM since you have owned it.

    Nick.
      
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  • Re: max rpm power curve

    by » 6 years ago

    My first thought is that it is running rich. At 3/4 throttle the jet needle is no longer metering fuel, you are operating on the main jet. What is happening to the Egt's? I would think they are probably reading low. If this is the case then downsize your main jets. Static you should be seeing 6250-6300 at 1050-1100F.
    Dennis
      
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  • Re: max rpm power curve

    by » 6 years ago

    Be interesting to know what your EGTs are reading Conrad...
      
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  • Re: max rpm power curve

    by » 6 years ago

    I agree that it may be a main jet problem. I'll try a smaller (155) jetting. I have 158s in now per catalog.
      
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  • Re: max rpm power curve

    by » 6 years ago

    If you have stock jetting that is correct with the temp/alt charts and it has operated properly before then I would suspect either too much Prop or deteriorating engine performance.
    A two stroke engine with needle bearings does not store well.
    Dennis
      
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