Mud Motor Prop

Discussion in 'DIY Marinizing' started by stretch1985, Aug 16, 2012.

  1. stretch1985
    Joined: Jul 2012
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    Location: Clearfield, Utah

    stretch1985 New Member

    I'm trying to turn a 5 HP horizontal shaft motor into aa mud motor and i was just wondering what would be the best prop pitch and drive shaft angle. also would it be better to have the ddrive shaft come straight off the engine or put a universal joint in between so the motor still sits flat.
     
  2. Erich_870
    Joined: Feb 2009
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    Location: Juneau, Alaska

    Erich_870 Junior Member

    You could go both ways with your motor, U-joint or not, it really depends on how high your boat transom is. There is a company called Stump Jumper who sells a straight shaft mud motor and there have been some threads recently on several duck hunting forums where guys have put these on higher transom boats and they won't run. The low oil sensor prevents it from starting. You can remove the sensor and add extra oil, which is what kart racers do.

    Adding a U-joint is what the rest of the long tail manufactures’ do, so the motor says flat.

    As for the right prop, Mud Buddy says you'll want a 6.5" x 4 prop: http://www.mudbuddy.com/Propeller Selection Guide.htm

    Because of your engine size there isn't much of a choice for pitch with mud props. They have different diameters for different hp engines, but the pitch typically is the same across the board.

    Erich
     
  3. stretch1985
    Joined: Jul 2012
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    Location: Clearfield, Utah

    stretch1985 New Member

    hey erich, thanks for your input. my motor is a two stroke so i wouldn't have to worry about the oil problem. i looked at the mud buddy website and seen that, i was just wondering if anybody had tried a different one that worked better.
     
  4. Erich_870
    Joined: Feb 2009
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    Location: Juneau, Alaska

    Erich_870 Junior Member

    How fast does your engine turn? It may be too fast for the mud motor prop. It's tuned for the regular RPM of a 5 hp 4 stroke.

    Erich
     
  5. stretch1985
    Joined: Jul 2012
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    Location: Clearfield, Utah

    stretch1985 New Member

    i just tached my motor, and at idle I'm running around 1400 and at full throttle it's around 9000 RPM's
     
  6. Erich_870
    Joined: Feb 2009
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    Location: Juneau, Alaska

    Erich_870 Junior Member

    Yeah, that's way too fast for these props. A typical 5 hp 4 stroke will only get up to 3400-3600 RPM. You are probably going to have to gear it down with a belt and some pulleys. :(

    Erich
     
  7. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    you need to look at the thread on turning a weed eater into an outboard .( some of the designs are 5 hp lifan)...at the hp you are using then a straight coupled 4 stroke @ 3600 rpm is the way to go but at 9000rpm on your 2 stroke you need some reduction say 3:1 or your prop efficiency is very low..give consideration to the availability of props in left and right hand pitch..a chain gear can reverse the direction and give reduction ( that what the thais do)
     

  8. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    Not same pitch!

    Just my 2 cents (worthless in canada!)

    Most of the 2 blade choppers you yanks use ARE similar pitch......BUT....

    The Thai guy's have a ton of options.

    Got mine through SPS's american distributor.......very helpful folk.
    (and i got a tee shirt)
     

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