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rockland213 02-23-2013 10:01 AM

Outboard boat motor???
Has anyone ever thought about building a bike with a outboard powerhead? 25-40HP They seem to be farly easy to find with bad lower units...and there not worth alot as boat motors.

4play 02-23-2013 10:36 AM

II've seen them in midgets back in the day. Today, since water cooled motorcycle engines are more common & typically motorcycle engines are made even lighter & more compact than an outboard I don't think you'd find any advantage.
What would you do for a transmission?

DirtyDog 02-23-2013 11:33 AM

Another difficulty might be that they are designed with a vertical drive shaft. Might be more difficult to transfer that to a horizontal transmission.

I'd love to see it tried though...:lurk

rockland213 02-23-2013 11:37 AM

[HTMLWhat would you do for a transmission?][/HTML]

Never thought about that. But after a little looking on-line they a pricey.

scrach that idea .

rockland213 02-23-2013 11:41 AM

It wouldnt need to be vertical . You could just make a addapter to turn the carb. Its a 2 stroke so it can run on any angle

Highside>Lowside 02-23-2013 06:01 PM

There was one that ran at Great Lakes Dragaway back in the 80s. Ran an OMC, IIRC. Much bigger than 25hp, however...

beachmike1 02-23-2013 06:54 PM


Originally Posted by rockland213 (Post 20792446)
Has anyone ever thought about building a bike with a outboard powerhead? 25-40HP They seem to be farly easy to find with bad lower units...and there not worth alot as boat motors.

Unless the engine is very old it is loop scavenged and will have a broad power band. The main issues will be mounting and power transfer. The problems with power transfer are basic engineering issues. Suitable transmissions can be found on older British or even Indian built Enfields and Harley's and their clones which have mostly separate transmissions. These usually have couches too. The PTO of the engine will have to be modified to accept a chain or belt drive to match the transmission. This is not hard but is not cheap for a one of. Same with engine mounts.all of this is basically engineering and fab.
As in the old commercial..if you have the time.......

Machine shop time runs about ninety bucks and hour and they have to take you cad files and make machine files which is usually a two hr job. So if you can tube jockey the design you can get it made. And it will not be cheap. And you will get a poor running fuel hog engine that is not optimized for its application..but you may have fun.

Lets face it. I made homemade bread, jam, marmalade and such. It is a hobby. Do I save money??? Only if my time and fruit are free.

But I have fun.

There is a dude that makes v twins based on Indian made Enfields. I think he sells them from 24k for a 44 hp bike. He sells a few a year. They are neat. He has fun. Australia I think.

One big issue. You can't register it legally in the us.

Salsa 02-23-2013 07:12 PM

I saw an outboard powered 2 wheel vehicle. As I remember, It was a bicycle with the outboard sitting high enough for the drive wheel (in place of the propeller) could be pushed onto the front wheel.

Good luck on your new wheels !!!!!!!!!!!!


FlySniper 02-23-2013 07:31 PM

Not an outboard, but do a search for the Tularis 800.

bk brkr baker 02-23-2013 07:45 PM

This one is in a sidecar, but, Kim Newcombe raced a 500cc solo version with some sucsess.

Fishenough 02-23-2013 07:55 PM

Another factor not mentioned is that outboard motors are not designed with any type of air filtering system. It's not to dusty on a body of water, so there is no design consideration for a air filter.

Those old 2 stroke mercs 6 cylinders had a fantastic, instant, power band; that on 2 wheels would be a blast

Frank from Quebec 02-23-2013 09:55 PM

You could also look at snowmobile motors, a 1000 twin or triple 2 stroke with about 160hp should be fun.

Owlseye 02-25-2013 08:05 AM

I'm not sure if it was common, but there were some roadrace bikes in the 70's pwered by 2 stroke outboard engines. There is one here in Edmonton that shows up occasionally in the vintage section of bike shows- sorry I can't recall who built it or owns it presently, but it was either an act of ingenuity or craziness, depending on your point of view. It had a monocoque frame (not tubular), used the engine as a stressed member, and if my (admittitly dim) memory serves, an Earles type front fork. I believe it did ok. I have no idea what he/they used as a transmission. I also recall some drag bikes with outboard based engines. Several others used snowmobile engines. Ah, the 70's. There was more to it than wide bottom plaid pants and platform shoes.

Sounds like a project for that old Evinrude at the back of the shed:lol3.
Good luck!

Salsa 02-25-2013 09:23 AM

In the late 50's or early 60's there was a 4 engined sports car. It had 2 Porsche engines front and rear with outboard motors driving the superchargers.


RedRaptor22 02-25-2013 04:36 PM

Anything is doable if you've got the time, the power density on a typical outboard engine is not that great though, I would look towards a snowmobile or jetski engine, usually more power per cc and already have the proper orientation...likely just as or even cheaper than an outboard.

I'd thought of something like that running at torque-a-verter setup, or even an automatic atv transmission, would make a fairly interesting drag or short trip streetbike.

I know an old man who pulled the worn out engine out of his old cb350 that had been sitting for the past 40 years and bolted in a p2 caterpillar diesel trash pump engine along with an torque-a-verter from a trencher or something, said it tops out at 70mph and gets about 120mpg lol.

Anything is possible, it's all time and resources, I'd really like to build a street legal briggs powered bike, done quite a few dirtbikes with them, had a suzuki 50 that'd top out around 50 with an 8 horse briggs lol.

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