small outboard prop question

Discussion in 'Props' started by volkswagen50, May 14, 2010.

  1. volkswagen50
    Joined: Aug 2007
    Posts: 15
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    Location: Holstein, IA. USA

    volkswagen50 Junior Member

    On a small outboard motor, say 5-6 hp two stroke, whats the prop speed vs/engine speed? Are they geared down? Are 4 strokes geared different, I'm thinking that four strokes do not rev as high as a two stroke would at max speed.
    What does a small outboard like that turn for rpm??
    Thanks!
     
    volkswagen50, May 14, 2010
    #1
  2. Jango
    Joined: Aug 2005
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    Location: Mid Atlantic

    Jango Senior Enthusiast

    I believe Max Motor speed for both the 2 stroke and 4 stroke is 4500 - 5500 rpm with 2:1 Gearing. i.e. Prop running half speed
     
    Jango, May 14, 2010
    #2
  3. capt littlelegs
    Joined: Apr 2010
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    Location: England

    capt littlelegs New Member

    2:1 won't be far out, for example a Yamaha 30 is 1.84:1, the deciding factor is the crownwheel and pinion size in a slim gearbox.
     
    capt littlelegs, May 15, 2010
    #3

  5. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    Some of the 4 strokes I've seen rev a little higher than the equivalent two stroke.
     
    jonr, May 22, 2010
    #4
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