Weed eater engine conversion

It might go faster with a good tailwind. We won't talk about the m to f ratio, for safety sake. The prop came from a rc hobby shop. I pulled out the string trimmer cable and tapped the hole with a 1/4x20 tap, then I put in a 1/4 x20vs1/4x28 stud which is secured with high strength permatex. prop is secured with 4 1/4x28 nut, 2 1/4 fender washers and 3 lock washers also 1/4 inch. We outfitted the boat with flashlight style running lights to keep us legal. To start it I wrap a cord counter-clockwise and pull with a steady not fast motion (full choke). Today it started on the first pull, but it doesn't always. Once it starts kill the choke. I run it oil rich right now at about 32 to 1 to make sure it gets good lubrication. Also, with just me in it I was able to go upstream at 1.8 mph with it idling and no throttle applied. If you're not in a hurry or just want a little assist with paddling, that is fine, and a lot quieter. Make sure the 1/4x28 section is long enough to accept all the necessary hardware.

 

Also, I think a shallower pitch prop would actually increase the achieved horsepower by increasing revs, which might actually increase the speed somewhat.

 

Check locally, but Graves RC in Orlando has the things in stock. In fact they have the best assortment I have ever seen.

 

Cut frame pieces, clamp as you want them , Drill for pop rivets while clamped. Attach pop rivets. Make base for canoe attachment. Study video to see how it is assembled. Simple. Use aluminum strip under plywood to brace fastenings.

 

I think a bigger prop might be more efficient.

 

Finally some videos.

Right to left is downriver, left to right is upriver. This was my wife's first time with this camera, so please be kind.

 

This engine would handle an 18" by 6" pitch ok but it would have a bigger profile than I was going for.

 

hey that works pretty good. Nice job.

Do you wear ear plugs? If it could be quiet I'd build one. It's an elegant, simple system.

 

Took ear plugs but didn't use them. Noise wasn,t too bad.

 

I placed a deflector to keep exhaust from me and it deflects some of the noise.

 

I have another question.
Is a 31cc Weedeater is a more powerful electric motor 30LBS? push

Second question, small propeller replacement Minn Kota can do?

Or what need to buy for a 31cc Weedeater?

Thank you

 

pgtcobra, 31cc Weedeater probably puts out about 1.2-1.5 horsepower. Are you putting it on as an outboard foot or running a shaft through the hull? Are you trying to save weight? If so take the gas over the electric.

 

mark wo, I forgot to tell you the engine mount is 1x2 angle aluminum pop riveted together with a sheet of 1/16 aluminum drilled out for the rotor and mounting screws. The pieces were clamped, then drilled and riveted while still clamped. Notch out the big hole for the magneto. Again, refer to video. I made a flywheel cover out of plastic using a heat gun, then sprayed on aluminum paint to match.

 

Hi hoytedow
Thank for your reply

For the type ... Outboard foot or shaft through... i don't know...
I would like made for fun and also to save money, since the batteries are expensive and heavy to install on a pedal boat.

 

pgtcobra, As you can see from my videos, I did neither. Instead I made the weedeater into an air propelled machine, at very little cost. It cost me a used weedeater, a 1/4 inch engine stud, afew nuts and washers and a model airplane propeller. All the rest of the parts I made from scrap I had laying about. My floor fan in the garage donated its front guard for the safety screen.