one day I had an idea to make a powered kayak i already had the motor and propeller so I bought a bran new kayak for $450 at gander mountain and started cutting holes in it, my dad freaked out and thought I was a dumb a#$....come to think of it I'm sure he said it out loud lol.
the motor I used was out of a 50cc polini pocket bike it is liquid cooled. I needed a pump to circulate water into the engine so I purchased a universal car windshield washer pump and i used a 12 v battery from a car jump starter to circulate the water to cool the motor when its running
the driveshaft tube and bearing is from a weed Wacker and the driveshaft itself is a solid piece of steel rod from the signs people put in your yard that say vote for (enter D-bags name here) as judge or mayor and I'll save this city!
the connection of the shaft to the motor is essentially a universal joint. basically I took a 1/4 inch craftsman swivel from my toolbox welded it on the shaft of the motor then did the same to the driveshaft
the propeller I lucked out with. my neighbor had it in there garage and gave me it. I found out it was an industrial food mixing propeller. it's a 3 inch 3 blade stainless propeller. i need something bigger because it seems like the motor doesn't even know its there and it runs with no load
the exhaust was original I just cut and re angled it to fit. also I disassembled the top end of the motor and flipped it because the exhaust would have been coming out at the bottom of the boat and might have melted the plastic bottom. so I made it exit the top
the throttle was attached via a bicycle break cable connected to my oar
problems I had with the set up were:
1. I originally used the weed Wacker cable as the driveshaft but it twisted in half so I used a solid rod and craftsman swivel it works flawlessly!
2. flooding...water would shoot up the driveshaft tube so I inserted a plastic sleeve around the driveshaft and some O rings on the shaft then used rtv silicone to seal any part where water would enter the shaft and shoot out when it was running
3.its really loud. I haven't fixed that problem yet but I'm thinking a tube attached at the end of the exhaust and inserted in the water will quiet it down
4. when the clutch gets wet it slips so I am going to seal the vent holes with jb weld or equivalent puddy so no water can enter. it doesn't hinder it to bad but you can feel it slip every now and then
Step 1: Video of It Running