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Old 08 December 2013, 15:22   #1
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"Up-propping" and idle adjustment

If "up-propping" is a real word, that is what I am doing - going up an inch and three-quarters in pitch. For the purposes of testing it, am I likely to need to play with the idle speed?

I don't have a 'fast idle' lever to play with and obviously want to avoid the engine stalling when I put in gear.

Its an ex-contract 30 hp Mariner-badged Yamaha (originally fitted to the Ark).

Thanks!
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Old 08 December 2013, 15:52   #2
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Inch and 3/4 ? That's an odd amount.

No, dont' touch the idle speed.
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Old 08 December 2013, 15:56   #3
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Inch and 3/4 ? That's an odd amount.
It's replacing a Piranha plastic prop that I inherited with the engine. The sizes seem to be based on hat sizes!
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Old 08 December 2013, 15:58   #4
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In which case, don't expect the plastic prop to be any benchmark for pitch-they slip like mad in my experience.
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Old 08 December 2013, 16:07   #5
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Uep. Like driving on ice.
The 'new' prop is a 'free' one so it might be a starting point.
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Old 08 December 2013, 16:09   #6
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on that engine does turning the choke knob not adjust the idle speed? im guessing its a 2stroke? my merc 25 used to have a choke that pulled out but also rotated for idle speed.
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Old 08 December 2013, 16:35   #7
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on that engine does turning the choke knob not adjust the idle speed? im guessing its a 2stroke? my merc 25 used to have a choke that pulled out but also rotated for idle speed.
That'll be idle mixture not speed, and it's a bad idea to mess around with it. Later motors don't hve the feature because people played with it, not knowing what they were doing.
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Old 08 December 2013, 16:39   #8
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Might be a starting point, check engine model matches first.

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Old 08 December 2013, 16:46   #9
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That'll be idle mixture not speed, and it's a bad idea to mess around with it. Later motors don't hve the feature because people played with it, not knowing what they were doing.
Just to let you know the old merc 25's with that know that pulled out and turned actually adjusted the timing to give the engine more rpm and was only used for starting from cold.
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Old 08 December 2013, 16:53   #10
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Sorry missed this bit off


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