Weed eater engine conversion

I didn't do anything to the gear box. I have not noticed any problems but I have not opened it up to check either.

Erich

 

Cant get a Rickshaw prop delivered to the uk cheap enough. So i have gone with the youngs T10.

My motor has a straight shaft and the bush for the end is all in one with the gearbox. I dont want the gear box as it increases rpm 1:1.2 and changes the angle. Orderd nylon bushes to replace the all in one unit, they need boring out.

Thanks everyone for the help, I will post some photos next week when I start making it.

 

Just joined the forum, after some lurking through the various posts. I have an Otter Stealth 2000 that I want to put a long-tail on that will push the full 550 lbs it maxes out at.

I noticed one other Stealth on here, from a few years back. Hopefully, he's had a lot of experience with the Stealth/engine combination by now, and I'd be very appreciative of any input. I haven't started on the engine yet, so I could go pretty much any way. I had planned to pretty much follow "ripped offs" plans as listed on page 6 of this forum.

I'm a newbie... just wanted to say hello. Thanks.

 

Newbie

Hi,

Just joined the forum and have browsed through this thread with great interest.

A friend of mine asked me to help him with a weed eater motor conversion to power his 10 foot inflatable boat. He had a design that he put together with a weed eater that was old and hard to start. He also installed a 8" diameter Sheakspeare 3 bladed propeller with what looks like a pretty steep pitch in the blades. No numbers on the propeller so can't really tell much about what the pitch angle is.

Using that combination I had a 24.2 CC Shindiawa weed eater that I retorfitted to his existing flexible curved drive shaft. I tried it in a 55 gallon drum and it seemed to work O.K. Then we took it to the local by-pass canal and hooked it up to his 16 foot bass boat (not the boat that this unit was intended for) just to see it it would push it around. Of course this unit is probably not powerful enough to push that large of a boat around. As we were running it you could smell the clutch as it was probably overheating.

Then I read on the forum that some people had used a lockup devise for there clutches. I made one and it made it harder to start out of the water and would not start with the unit lowered into the water. We started it out of the water but when it touched the water it stopped the motor.

I have read where some of the guys are using the Youngs T-10 2 bladed propeller with success and thought we might try that and see what happens.

Of course, most of the guys had said to use a 31 CC or greater motor. The Shindaiwa motors are typically pretty strong for their size but may not be up to the required power needed for this application.

I have access to the necessary machine tools to make any necessary adapters, parts etc. that would be required to put one of these together.

I would appreciated any and all suggestions, keeping in mind that the ultimate goal is for my friend to have a reliable weed eater powered devise for his 10 foot inflatable boat.

Thanks in advance for all your help.

John

 

QUOTE a reliable weed eater powered device............not possible get something 100cc+

 

Welcome to the forum, American_Yankee and HelicopterJohn.

 

Thanks for the Warm Welcome

Hoytedow, thanks for the warm "welcome". It's interesting that the last two guys to post are involved in aviation, and boats. HelicopterJohn is obviously into helicopters, and the "American Yankee" in my user name comes from the brand of my small private airplane... It's an American Yankee Clipper. I'm very much a southerner.

I appreciate all of the "free" technical information from those that are willing to share their research, and results so freely on this site. Hopefully, it will help the rest of us, that are in the infant stages of just getting started, not to re-invent the wheel again. I'm trying to contact "ripped off", to see if I can get his latest modifications to incorporate into my build. Right now, I have a Ryobi 31cc that I'd like to put a shaft and prop on, to see what it will do on my Otter Stealth 2000 duck boat. Thanks again.

 

if you insist on using a weed eater then remember that many of these engines were used in model boats and a prop that loads them correctely to the right rpm can be got from a model shop..only may be 3 in in diameter but will give the right load. If you can weaken the springs in the clutch this will still let you start it but prevent the dreaded slip which is really due to too big a prop and hence an overload. you need a rev counter on it to see you are getting up to 7000 rpm ...too big a prop and too low revs is where the problems start .

 

Don't llisten to this bad advice. Pistnbroke has been saying this same thing for some time now. I've built 4 with weed eater engines and all 4 are still working just fine. The main motor I use now is going on it's third season and it gets used frequently. Only maintenance so far is changing the oil at the end of every duck hunting season.

The engine chosen is a big deal. My 31 cc Ryobi (copied from Ripped Off) just doesn't run as well as I would like. I then went to a 51 cc motor (Chinese design - Duropower unit) and it runs strong with no issues. Next motor was a Honda mini 4 stroke motor (GX35) and it is the go to motor. No issues, has run great ever since.

There are also many commercial motors out there using these smaller engines and many are happy with the results. Don't listen to someone who hasn't built one, listen to those of us who have and have had great success.

In defense of Pistnbroke, I wouldn't use any of these motors as a true mud motor. In clean, and somewhat weedy water, they work great. Pushing a 16' johnboat through mud flats won't work.

Mark

 

QUOTE Don't listen to someone who hasn't built one,
Well thats funny all the pictures are on here...
QUOTE Next motor was a Honda mini 4 stroke motor (GX35) and it is the go to motor. No issues, has run great ever since.
Well well great supprise not a 7000rpm peaky torque 2 stroke ..a 4 stroke with a steady torque output

So we are all in agreement then... such bliss ..its still all down to getting the prop right and how much weight you want to lug about ....

 

I thought all your motors were bigger than the weed eater motors most consider to be weed eater motors. Please note, the GX35 IS used as for commercial weed eaters and it is significantly smaller than the 100cc motor you said had to be used for reliability.

Also, I have spun props bigger than those used for RC boats. The Youngs props work well but being cast aluminum, it doesn't take much to break one. There are better choices out there if someone does a little digging.

My whole point in all this is small weed eater motors work. By small I mean under 50cc. As with all things in life, it takes a good motor not a cheap weed eater motor tomake it work. One has to be clear as to what this motor will, and will not do as explained in my post above. If all you want is a lightweight motor (under 20lbs), that will push a boat 6 mph reliably, this is the way to go.

What's the smallest motor you've built? What does it weigh? How fast will it push your boat?

Not trying to get in a pissing match but what you say is not true. You don't need a 100cc motor to be reliable and to work. That is your quote, you wrote it, not me, and the one I disagree with.

Mark

 

There and I thought it was the yanks who said no substitute for cubes.....
The bigger the motor the easier it is to find a suitable prop..4 stroke less fickle than 2 stroke . A cheap 2 stroke thats a pig to start as a weedeater is no going to make a good boat motor.....

Everyone does what they want. my advice is to get something bigger as the whole project becomes more satisfactory and less likley to end as a failure.
If you dont have access to a lathe carnt weld or cut a thread then the job is going to be hard unless you got lots a $$$$

 

Like I said, my second motor with the 50 cc Duroprop 2 stroke motor is still running strong. Young's T-10 prop being used on this one. Not one failure, not one time has it failed to start (except when I broke the pull start) and I use it frequently in well below zero degree F. weather.

I don't have access to a lathe and didn't need a lathe to build 3 of the motors. I didn't need to cut a thread and I don't own a welder. I did have the place I purchased weld the skeg to the drive tube and that cost me $20, not $$$.

Your experience is not the same as mine. I'm certain your motors run well and advice you provide is good. I just have a diferent point of view and my experience has been different than yours.

As far as no substitue for cubes, I'm a yank and have a 2.5 liter 4 cylinder motor that is putting out 375 - 400 hp in the fun car. Way more hp than some of my buddies who have big V8's.

Mark

 

Output shaft

Hi Guys,

The current configuration is a curved shaft weed eater with a squared end flex cable drive with a minnkota bracket to adjust the propeller alignment.

Would it be better to make some type of bracket and use a mud motor design with a straight shaft that would mount to the transom of the inflatable boat?

I am thinking of having my friend order a T-10 Youngs Prop. Of course, I could adapt it to either the curved flex shaft drive or a staight mud motor drive.

Any specific motors, prop conbinations, clutch/no clutch and styles (weed eater curved flex shaft or mud straight shaft) you guys have used would be appreciated. i.e. brand and model numbers and and possible places where these can be purchased.

i.e. SAMPLE: Ryobi 31 CC Model No.????? Curved FLEX Drive Shaft With Clutch with Youngs T-10 Prop and what type and length of boat you have used this application on. And then add any vendors or places where these items are available.

Keep in mind that this would be for 10 Foot Inflatable Boat that my friend wants to use for casual bass fishing.

Your help would be surely appreciated. Thanks in advance for all your help.

Thanks,

John

 

I wouldn't run it with the curved shaft. Get a 1" aluminum tube, add some bonze bushings and make the long shaft, or get a gear head and do a short shaft if you want something smaller.

Mines a Ryobi BC30 using the short shaft and gear head, young's T-8 prop, homemade transome mount and tiller handle. I run it on my Marsh Rat duck hunting boat.

Here's more information on it: http://www.youtube.com/watch?v=2gknDrRJa2c

Erich