Bike engine in small runabout

[Danielsan]

Some one ever tried to put some kind of bike engine, say Honda CBR fireblade 900cc or + into a small <20 ft runabout. Could use existing clutch and gears, chain and chainwheels under some kind of chain guard cover.

I was thinking about this as the IRS got a bit deep into my pocket and I will have to put aside my bigger project for a year.

So I am thinking a bit smaller for a while.

greetz,

[marshmat]

Marinized motorcycle engine? I don't see why not; so long as you have a good idea what you're doing. It's not the motor so much as the drivetrain you'd couple it to that would be the difficulty, I would think.... with a 900 bike engine, it's probably low on torque but good at the top-end, so maybe pick up a pump from a dead jet-ski and tack your marinized bike motor onto that? Just a thought.

(As an aside, I toyed around with the idea of putting a bike engine and jet-ski pump in my boat after she blew up her Suzuki outboard a few years ago.... the performance numbers looked great, but I found a new outboard before I had the chance to go hunting for wrecked jet-skis. Perhaps for the next one...)

[PowerTech]

Thats exactly what honda did in there new wave runners.They put a tubo on it to.http://www.buyandsellboats.com/previ...&uid=431473500 I would think a 20 footer would be to mutch boat.But a 14 or 15 would be cool.How about a used carolina skiff with a jet pump out of one of them yamaha jet boats so the pitch of the screw would be close enough and a big street bike motor.You could couple it by welding a sproket to the pump shaft put the output sproket on the engine up to it face to face then cut a double row chain to wrap around it and pin the master link and you are all set.

[Danielsan]

In a general way this is what I was thinking about, but as the jetunits are not easy to find in Europe Belgium I thought about some straight shaft with a sproket weld onto it.

Indeed 20ft would be to much.

Don't know how I would put it in reverse, but for a small thing like this it would not be necc?

some thinking has to be done....

need to get some sleep now.

Thx

greetz

[marshmat]

I've heard of 20-footers without reverse, but I'd certainly want the F-N-R transmission for docking. Straight-shaft with a chain driven sprocket would probably work, with a bit of creativity, patience and careful measurement. You'll probably need the sprocket system to reduce the rpm maybe 2:1 or something (have to guess from the motor specs though). You'd have to spend a fair bit of time picking props, too; a good prop dealer will be of help. Good luck!

[Arrowmarine]

HMMMMM I had the weird notion to couple my KZ 650 engine with an outboard jet pump welded to the hull of a small 12' deathtrap. I dismissed it as crazy. Might have to re think this one.......

[Danielsan]

I won't say it isn't crazy, but it's worth the try

[BigD]

Interesting thread .... i just sold a '76 Kawasaki KZ900 that I had built to a bit over 100 hp (not much to todays bikes). The power band really kicked in at 7000 and ran to the 9000 red line. Seems that you could do something with the original tranny for the correct gearing and keep reverse. Then you have the engine on my Harley that runs a much lower rpm and much higher torque ........ hmmmmmm ...

[mackid068]

Any more than 16 feet would be much to large for a motorbike engine unless you want a slow tender-type boat or a scow or, perhaps, a fishing dory.