Weed eater engine conversion

Discussion in 'DIY Marinizing' started by Ward, Jun 2, 2003.

  1. Lunatic Fringe
    Joined: Jul 2009
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    Location: Fort Benning GA

    Lunatic Fringe Junior Member


    Saw your post and decided you were RIGHT, but take a look at my little weedeater conversion. May not be a mud-motor but it could be with a straight shaft. See if it gives you any ideas. What are you going to put your mud-motor on, a duck boat, canoe, flat boat ???? A simple "Y" mount with bungie cord would hold my motor in a mud configuration mount. Just use the straight part of the shaft that I discarded in my conversion. Or put 2 straight shaft (quick connect types) together to make a longer shaft if needed. See my post today Sept 6, 2010--- (Lunitic Fringe)
     
  2. Lunatic Fringe
    Joined: Jul 2009
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    Location: Fort Benning GA

    Lunatic Fringe Junior Member

    Stock Ryobi 26cc Weedeater Conversion Motor

    Hi folks, I've been reading this forum for several years now and decided to stop in and show my weedeater conversion motor. Contrary to many experts on here, I built mine using a Ryobi 26cc from Home Depot $98, and they sell replacement powerheads for $79. Some say 32cc is minimum size that will work. Well my 26cc has been pushing my canoe around for 2 yrs. now, and runs just fine. I simply removed the upper shaft-half (quick-connect type) and installed the lower curved shaft into the power head (you'll have to notch the tube to allow it to fully seat) and then re-tightened the the collar. I welded up a transom mount, and a weed-guard for the nylon 3 1/2" prop. The prop was a $5 close-out item from a local boat shop selling off it's out-dated trolling motor accessories. I have no idea what it originally mounted to, and neither did the shop, so that's why I got it for $5. I also welded a nipple to the original muffler, capped the old outlet on top, and routed the exhaust down the shaft so it exits underwater, to quiet it down a bit. I used copper 1/2" tubing so it will never rust out. Keep your prop size to less then 3 1/2" and the 26cc motor works fine. I utilized the original throttle handle on my tiller-arm, and mounted the D-ring handle 180 degrees from the original position to make a handy tote-handle. The local rednecks where I fish, couldn't believe I made it out of a weed-eater. I weigh near 300 lbs and and one of them said, "you don't think THAT little motor is going to push your big butt around on this lake, do you???" I just laughed and and said--watch this, and throttled off into the distance. They actually cheered for me the first time they saw me hook it to my canoe and launch it for it's maiden voyage. When I came back a half hour later with a nice string of fish, they all wanted to know how much I'd charge to convert their weed-eaters too! And yes, it has plenty of thrust, you won't pull any skiers but it's certainly adequate for buzzing around on the lake to get to your favorite fishing holes.

    [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]
     
  3. Lunatic Fringe
    Joined: Jul 2009
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    Location: Fort Benning GA

    Lunatic Fringe Junior Member

    I sent a reply to Mark Wo too. Here's my little Weedy-Conversion using mostly stock parts. Total cost was about $125 INCLUDING A BRAND NEW RYOBI WEEDEATER FROM HOME DEPOT ! And if I ever burn it up, I can pop on a new power-head for $79 (also available off the shelf from Home Depot).

    Hi folks, I've been reading this forum for several years now and decided to stop in and show my weedeater conversion motor. Contrary to many experts on here, I built mine using a Ryobi 26cc from Home Depot $98, and they sell replacement powerheads for $79. Some say 32cc is minimum size that will work. Well my 26cc has been pushing my canoe around for 2 yrs. now, and runs just fine. I simply removed the upper shaft-half (quick-connect type) and installed the lower curved shaft into the power head (you'll have to notch the tube to allow it to fully seat) and then re-tightened the the collar. I welded up a transom mount, and a weed-guard for the nylon 3 1/2" prop. The prop was a $5 close-out item from a local boat shop selling off it's out-dated trolling motor accessories. I have no idea what it originally mounted to, and neither did the shop, so that's why I got it for $5. I also welded a nipple to the original muffler, capped the old outlet on top, and routed the exhaust down the shaft so it exits underwater, to quiet it down a bit. I used copper 1/2" tubing so it will never rust out. Keep your prop size to less then 3 1/2" and the 26cc motor works fine. I utilized the original throttle handle on my tiller-arm, and mounted the D-ring handle 180 degrees from the original position to make a handy tote-handle. The local rednecks where I fish, couldn't believe I made it out of a weed-eater. I weigh near 300 lbs and and one of them said, "you don't think THAT little motor is going to push your big butt around on this lake, do you???" I just laughed and and said--watch this, and throttled off into the distance. They actually cheered for me the first time they saw me hook it to my canoe and launch it for it's maiden voyage. When I came back a half hour later with a nice string of fish, they all wanted to know how much I'd charge to convert their weed-eaters too! And yes, it has plenty of thrust, you won't pull any skiers but it's certainly adequate for buzzing around on the lake to get to your favorite fishing holes.

    [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]
     
  4. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Think you done a great job ...love the g clamps for a mount and use of the original parts ... but I think the secret of your success is the right propeller ...so many I think are over propped...
     
  5. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

  6. muddin redneck
    Joined: Jun 2009
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    Location: Muscatine, Iowa

    muddin redneck DO IT IN THE MUD!!!

    lunatic
    nice job on the weedeater motor have you ever took a gps with you so you could get a speed reading
     
  7. Lunatic Fringe
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    Location: Fort Benning GA

    Lunatic Fringe Junior Member

    Thanks pistnbroke, you're right, small prop with low pitch is the key to keeping the rpm's in the right range for maximum thrust. After I built my conversion and found out it worked better than expected, I wanted to know why I had succeeded where so many others had failed. That nylon prop just happened to have all the right characteristics needed for success. I bought a book called "The Propeller Handbook---by Dave Geer" (ISBN 0-87742-988X) and it helped me understand the engineering involved in choosing the right propeller for a given motor. Anyone converting motors for boat use should give it a read. If I could find the manufacturer of my nylon prop, I'd buy out their entire stock of the prop I have on my motor, weld up some transom mounts, weed-guards, and tiller handles and make a kit to convert the Ryobi's into ultralight outboards. If I could sell the kits for less than $100, I'm sure they'd sell like hotcakes! I already have other canoeist, kayakers, and Jon-boaters asking me to do conversions for them. A Chinese company makes the next closest outboard, but they're twice the weight and cost $600-$800, plus they're water-cooled (another unnecessary headache). My next project is adapting the motor to a large surf-board-like boat to use as a diving platform to take divers to and from their dive spots. The biggest problem so far is water-proofing the electronics. I'll post a photo when it's ready for ocean testing.
    Cheers,
    Jack
     
  8. Lunatic Fringe
    Joined: Jul 2009
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    Location: Fort Benning GA

    Lunatic Fringe Junior Member

    Bumble Bee Outboards

    Thanks for the pics of the old bumble-bee outboard. I don't think they make it anymore, do they? The prop is even smaller than mine (by about half). It also made me realize I can eliminate the tiller arm on my conversion and just make a throttle-conversion for the D-handle. And still have a convenient way to tote it back to camp or vehicle.
     
  9. Lunatic Fringe
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    Location: Fort Benning GA

    Lunatic Fringe Junior Member

    Speed??? Maybe 4-6 MPH???

    No, but that's a great idea! I'm going to estimate top speed at around 4-6 mph, a little faster than a brisk walking pace, on my heavy fiberglass canoe + 300lbs of ME onboard. I don't see any reason why a lightweight kayak, with a 100-150 person onboard shouldn't be able to nearly double that speed. Two of them running side by side on a carbon fiber sport-yak would probably plane-out and achieve some real speeds!!!
     
  10. Mark Wo
    Joined: Dec 2007
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    Location: Minnesota

    Mark Wo Senior Member

    How about making a nice silicone mold of the prop you have and making your ownprops? Very, very easy thing to do and you could make many from a single mold as the nylon could be poured into the mold and it doesn't require huge heat like aluminum or some other metal.

    Mark
     
  11. Bob Eames
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    Bob Eames Junior Member

    My thoughts exactly!!!

    Bob
     
  12. Lunatic Fringe
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    Lunatic Fringe Junior Member

    I can make a mold, but never heard of "pour-able nylon". I thought nylon was like a plastic injection molded process, involving expensive metal dies and heat and tons of pressure???? Tell me where I can get a nylon in a liquid state to pour into my molds, and I'll give it a shot. I already have a small aluminum foundry I'm setting up, but I don't have much hope of it producing a prop with the same weight and toughness as this nylon prop. It took several good logs "hits" before I added the weed-guard, and it escaped basically unharmed except for a few scratches. It weighs probably half of what an aluminum copy would weigh. The boat shop that sold the prop to me said it came out of a box of very old MinKota stuff from the 50-60's. They've gone to much bigger props these days, and the new props simply will not work with these little 26cc Ryobi's at all.
     
  13. blad3
    Joined: Sep 2010
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    Location: Australia

    blad3 New Member

    any know where i can get bevel gear in Australia Melbourne as they are not cheap to import. Or is there another option instead on bevel gears
     
  14. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    blad3 ..tell us what you want the beel gears for ratio etc ..which engine are you using ..if its big enough use a chain......why complicate the system with something that can break.....
     

  15. dinoa
    Joined: Oct 2007
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    Location: florida

    dinoa Senior Member


    A PU fiber resin might be suitable to cast the prop. Leading edges for wooden ultralight aircraft props are made this way. I remember reading some years back that a product called "uralite" was used.

    Dino
     
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