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My 582 blue head refused to start after a few days, and I noticed the marks on the oil pump housing were not lined up correctly with the throttle at idle. It was set to putting a tad more oil than the recommended setting. A little while ago I rebuilt the carbys and had set it up iaw the Rotax manual, including a balance, and it started beautifully, but I guess their was a bit of slack in the oil pump cable which I missed and so it was slightly out of alignment.

I adjusted the oil pump marks correctly and then attempted a start. The engine started almost immediately, but idled at 3,500 instead of 2-ish.. My question is why did the idle increase as a result of (only) adjusting the oil pump line? Is the mixture that critical - I would have only adjusted the oil pump marks about 3/16" . I'll go through and do a retune, but I was surprised that the idle speed increased with only an oil pump adjustment ..
  • Re: Idle speed increased when oil pump adjusted.

    by » 10 years ago


    The change in idle rpm is not a result of a small change in the oil pump setting. You have disrupted the adjustment of the throttle cables. If you check the idle stops you will probably find that the slides are not contacting the stops. At idle the slides should be resting on the stops with enough slack in the cable to allow you to adjust idle speed with the idle stop screws. Carry out your carb sync being carefull that you retain slack in the throttle cables at idle.
    Dennis

    Thank you said by:

  • Re: Idle speed increased when oil pump adjusted.

    by » 10 years ago


    Thanks so much Dennis - you are absolutely correct. When I checked the 1mm slack that is supposed to be in the cables it wasn't there so went looking for where it had 'gone'. Turns out I had disrupted the throttle cable and somehow the outer cable at the hand throttle had become caught where it enters the hand throttle body - I hope that makes sense. bumped the idle revs up to 4,000. I popped it back, readjusted the slack to correct tolerance and rebalanced the carbs - engine is back to its beautiful self.

    Appreciate your response, Thanks !

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