My buddy Jay had a 4cycle Ryobi weedwacker his dad gave him that was never used. He preferred the electric for yard work so this thing was only run once. We bought a Waterwacker conversion kit off Ebay for $100.00 and swapped the wacker over to marine use. While I was doing that, John (Jay's dad) built a small dingy for the motor. I finished the motor up and took it over to John's house today and we put em both together. We put gas in the motor and it fired right up! All looks good and we will try it out next weekend. This is not a retrieval boat. We have electric boats we use for that. This will be used to set buoys for a race course. Init cute! HAHA!! Brian

LOL; I don't know about cute, but great job of re-cycling. GOOD on ya!

Thanks Dennis, My brother says it looks like an old Popular Mechanics "build this boat" project! Don't care, should do the job... Brian

... Take that as a compliment Brian. Some of those old Pop.M. projects were pretty kool.

Have you tried it on the water yet ? I have a brush cutter lower unit like you used.The shaft is long ,but I could cut it shorter and put a shorter flexshaft in it from another trimmer.The shaft and engine looks the right angle so the engine gets enough oil to lubricate it.
Just wondering if that prop will over work the engine and heat it up. As you might remember from other posts I build a Homelite powered one with a curved shaft and a 6"

trolling motor prop.Engine didn't seem to heat up any more than it did as a weedeater,with that prop on.

Since I got interested in building another weedeater boat motor again,after seeing yours,I've been looking for a four cycle instead of the two cycle I made.I remembered seeing one at a neighbors yard sale last year and I stopped and asked if he still had it. He did and sold it to me for $10. He said it was only used one season and last season it would start and idle ,but bogged out and shut off when trimming.It's really clean and looks new.He bought a Husky and didn't want to bother fixing this one.Maybe his Husky will act up and I can get it cheap.I don't know much about four cycle trimmers, but will try to get it running. It has the upper shaft with the throttle on it,so I guess I'll use it for a handle like you did and I have a long brushcutter shaft that I could shorten and use a shorter flex shaft.He took the starter handle to put on another trimmer so have to get one.This can also be started with an electric starter,which he didn't have.I'll still have to get a transom mount and a prop like yours if it works really good instead of the plastic trolling prop.Just waiting to see how yours works on the water.Also have to find another small boat.
[attachment:1]2014_0510troybilt0001.JPG[/attachment to put it on.

I hope you didn't leave the engine in the same position as it is in your pic.The cylinder has to be up as in a normal trimming position or the engine won't get proper lubrication. The engine should be turned up and then turn the shaft with the prop on.

Good point the only 4 strokes that can run inverted are the Hondas.

Actually we figured that out about the motor direction, thanks. The kit I bought off Ebay came with a CCW prop. WRONG! We finally got a CW prop and tested the boat out. The prop is way too deep and the motor is pulling down bad. If you raise the motor to where it runs right, it puts all the weight of the motor way up in the air. I have the unit apart right now for some modifications. I'm cutting 6 3/4" off the down tube and flex. The game here is to get more of a surface drive performance out of it. I had to buy a 1/4" fuerrel and am making a 1/4" round to 5mm square shaft to go from the fuerrel into the bottom of the clutch. I'm also machining an adjustable swing clamp for the down tube so the prop height can be adjusted and locked off more securely than the plastic junk that came with the kit. I'll post more pics when she's done. Should be by next weekend as the boys are crying for it now after a day of using it already. SHEZZZzz....... Brian

No eBay APP ID défined in Kunena configurationNot sure of using a surface drive setup on it as the motor doesn't have the rpms that are put out by an r/c boat engine.You might end up with a gas powered egg beater. The prop I used in a submerged setup as on a trolling motor and it was a Minn Kota vanishing trolling prop and it didn't tax the Homelite 25cc I had.The prop fit the weedeater shaft and all I had to do was get a hole drilled in the shaft to accept the pin that came with the prop and found a nut with the nylon in the center for it.It wasn't fast,but got me out there and back.

I have the 25cc Troy Bilt trimmer I may build into another boat motor ,but would like one a little bigger. I saw troy Bilt has a 32cc trimmer I wouldn't mind getting a hold of.If I were to build another two cycle boat motor, I'd get a trimmer engine that is a full crank and get chipbreakr to mod it for more torque and water cool it.I'd use a water pump to keep it cooler,like I've used in an r/c boat with with a clutch and add a water pickup tube. I'd also route the exhaust into the water as was on a Cruise n Carry outboard I had.
Imay also strip down the Troy Bilt I have and take off the flywheel and ignition module and add an electronic ignition and built a big r/c airplane with sufficient wing loading to handle the engine.