Thai Longtail/mudmotor With 6hp Lifan/honda

Discussion in 'DIY Marinizing' started by pistnbroke, Feb 26, 2009.

  1. riverrat87
    Joined: May 2010
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    Location: haleburg, alabama

    riverrat87 New Member

    Hey guys, I'm attempting to follow in yalls footsteps with a 6.75 briggs off of a pressure washer and I'm not sure how to figure out what sprockets I need for the right gear reduction. Any ideas? Thanks in advance.
     
  2. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    Keep the B&S running at 3600 Rpm.
    Now you need to know the prop Pitch, and Diameter.
    Then you get the info on the load that will create.
    Then Gear the engine to the Prop using percentages.
    Then convert the percentages so Sprocket sizes.
     
  3. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    anything around 2 to 3 to one seems ok depends what prop you have to hand you could try to match it . .I think my big cog is 28 teeth small one 12 ..if you go much bigger in teeth the large cog gets physically quite big . If you can do a double chain its even better. I think Mc Master Carr have a selection of cogs mail order

    You can get b and s with reduction gearbox attached
     
  4. riverrat87
    Joined: May 2010
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    Location: haleburg, alabama

    riverrat87 New Member

    I haven't got a prop yet, should I go with a three blade or two blade
     
  5. rmenasco
    Joined: May 2010
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    Location: Florida

    rmenasco Junior Member

    Pistnbroke,

    I have really been looking around a lot on the internet and I found a company over here in the states that is commercially selling the same thing that you have built for around 1000.00USD

    Here is there site....

    http://www.scavengerbackwater.com/
     
  6. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    A bit different, but it's powered by a GX270...
     

    Attached Files:

  7. Ed-H
    Joined: Mar 2010
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    Location: Montana

    Ed-H Junior Member

    Great tease Agro.......where's the rest of the photos???? Only two photos? That's down right wrong!!!
     
  8. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    Tease continued...

    Ok folks....Got her ready for the big race. Was a feat by our race team!

    Here's some photos of the completed boat in action.
     

    Attached Files:

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

    Agrodyne labs Junior Member

    Short vid. of boat.

    Testing & setup amounted to about an hour the night before race...Many changes in the works! If anyone else is thinking about this sort of craft, i'd love to hear about it!

    Have lots of photos, and video. Most vid is too large to post here, see what i can do!

    www.agroracing.com
    fauxydan on FB
    aggressive salmon bathtub race team on FB
     
  10. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    I guess .mp4's won't load....Bummer.
     
  11. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    BTW...Top speed over 3-4' swells in straight of georgia (Nanaimo BC) was 27mph for first test run...With careful setup and testing, engine and prop work & hull tweaking and fairing , I believe 35mph is easily attained with our present GX270 (honda) Direct drive, 18" behind the transom prop, clutch for neutral only, cable steering, Flat trans. pad w/ swappable pads , planning V hull , etc...
     
  12. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    Also....In photo of clutch area, notice that we put the thrust bearing before it , way up front! No need to have it at the prop. Keep it high and dry. All that is required at prop end is needle bearing and seal. Keep that tube skinny and simple! Our shaft is tube with solid shaft ends only. Runs in the carrier from a 15hp O/B milled down and threaded to insert in shaft housing. That way we get to use easily available marine parts and replace seals. Clutch is 2 piece - drive and driven... drive supported by engine output shaft, driven by self centering sealed roller bearing just on the engine side of the thrust bearing. Works well, and robust, replaceable.
     
  13. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    Hey PISTON BROKE!

    Why don't the Aussi's compete in bathtubs anymore? The NZ boy's are becoming strong competitors again! I would love to see some down under thunder next year...
     
  14. FMS
    Joined: Jul 2011
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    Location: united states

    FMS Senior Member

    Post the video with youtube
     

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

    Agrodyne labs Junior Member

    Will try that! Most is available on our website www.agroracing.com or FB page aggressive salmon bathtub race team....I will set up to post on youtube as well.
     
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