14' ski boat to convert to inboard w/Motorcycle power

Discussion in 'Inboards' started by kshort12, Sep 1, 2006.

  1. kshort12
    Joined: Sep 2006
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    Location: Oregon

    kshort12 New Member

    OK, I'm brand new but have done some research. Looking for advice, opinions, links etc. on my most recent project.

    I picked up a Glasspar G3 ski boat (13' 6"), originally designed for outboard motors around 60hp. It has a front bench seat with a center support, then another passenger area.

    Goals: Would like to achieve 60mph, 3-passengers, and some water skiing.

    Tentative design parameters:
    1. A 900-1000cc liquid-cooled motorcycle as a donor, engine to be mounted sideways in the rear of the boat with the sprocket facing forward.
    2. An inboard prop and shaft with the prop mounted as far rearward as possible and with as shallow an angle as possible, with the front of the shaft lining up underneath the sprocket from the transmission.
    3. The motorcycle chain would be shortened, reusing the rear sprocket as well, to drive the propeller shaft.
    4. Would mount the entire cooling system from the motorcycle, with radiator and electric fan, and provide a suitable mechanism for air intake and evacuation.
    5. Would keep the clutch, transmission, and throttle from the motorcycle, and modify it to be used from the driver's seat.
    6. Mount a rudder on the transom, with a simple cable-operated steering to the boat's steering wheel.

    Notes:
    a) Could adjust final drive through choice of prop, choice of which gear to run in, or size of sprockets on drive. I haven't done all of the calculations, but of course that will also depend on which engine I choose.
    b) Other bike features would be retained, such as starting/charging system, modified exhaust, fuel system, etc.
    c) Don't know yet how to rig the shifter, but I assume some type of cable-operated setup could work.

    Thanks in advance for your comments!
     
  2. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Interesting idea; there has been some talk of similar projects on here before (try 'motorcycle engine' in the search box). I don't see a reason why it can't be done, provided you take due care to make everything safe for boat use. That's the tricky part, is making it safe to use in a wet enclosed space where fuel vapours like to collect. I'd be interested to see how the bike tranny works; marine gears are usually just f/n/r and sometimes two forward speeds. Bike's usually 5 or 6 forward, plus neutral. (You might want reverse....)
    So exercise due caution, make sure you're doing things in a way that the Coast Guard won't hate you for, but I'd say if you think it out well it just might work.
     
  3. Frosty

    Frosty Previous Member

    Exellent,-- I love projects like this,-- dont forget a thrust bearing on the shaft. Apart from no reverse I would say its possible. I am not sure of 60MPH though. 6 cylinder Honda Gold Wing?? You need torque, rather than a 12000 RPM wizzer.

    I would also be a bit concerned about cooling . Motorcyles even the water cooled ones still obtain a lot of cooling by air. You could say that it is water, oil, air, assisted cooling. A water to water heat exchanger might cure that though.
     
  4. kshort12
    Joined: Sep 2006
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    Location: Oregon

    kshort12 New Member

    OK, thanks for the help.

    1. I will do some more calculations and make sure I know what donor bike/engine to look for. I don't want it too heavy but I would like to get close to the 60mph (50-55 might be OK).

    2. Cooling: I have to decide between a semi-open engine bay behind the front seats or build a cover around the engine once it's mounted in place. I might look at expanding the cooling capacity with a larger radiator and bigger fan. With a combination of vents or scoops and fans, I'm hoping the cooling will be adequate and...

    3. that should also help with the engine ventilation for safety purposes. I know about the flame arrestor on the air intake, but what other elements will an inspector look for that I should take care of?
     
  5. Frosty

    Frosty Previous Member

    You might want to think about mounting the engine up high like a drag boat. I dont know if that might soften your US regs but it would be out in the open. It would also put the engine into the environment from which it came, plus these engines can look real nice. Immagine a Gold Wing engine there with 6 pipes stickin out. Head turning if nothing else!!
     
  6. kshort12
    Joined: Sep 2006
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    Location: Oregon

    kshort12 New Member

    OK:

    No reverse, no big deal. That's what the paddle is for.

    According to my research, all motorcycles, with the transmission still attached and using the original sprockets, provide way too much gear reduction for use in a boat. That means that no matter what bike I choose, I will have to adjust the final drive by changing the stock sprockets.

    I figure I need a donor bike engine that produces at least 80hp, preferably a chain drive (I suppose a shaft drive could be converted), liquid cooled.

    Suggestions on a donor bike would be appreciated. Nothing too expensive. Also, what's a good target for prop pitch, diameter, and max rpm for a small, relatively lightweight boat to go 60mph?
     
  7. tuantom
    Joined: Jan 2005
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    Location: Chicago

    tuantom Senior Member

    I have always liked the Suzuki GS1100/1150's from the 80's - very torquey and tough . I don't believe they were liquid cooled until '85 or '86; but these are great dragbike engines and have lots of parts available - both stock and performance. I see these bikes around for a good price from time to time.
     
  8. Toot
    Joined: Jul 2006
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    Location: Chicago

    Toot Senior Member

    I was looking for a motor for an MG-Midget project. I narrowed it down to a Suzuki Bandit 1200 or a Kawasaki 1100+. Both are very available on the used market, as the engines have been around forever.
     
  9. Frosty

    Frosty Previous Member

    Toot. If Kshort12 will forgive me what are you doing with an MG midget?
     
  10. moTthediesel
    Joined: Apr 2006
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    Location: 1k Islands

    moTthediesel Junior Member

    I think that's a v. cool project!
    I know the boat well, as I have owned a G3 with an original white Merc 70/6 for 30 years, fun little play boat --
    There are lots of bike motors available that will make 100+ hp, so I don't think your performance goals are out of line. My favorite might be a Yamaha V-Max V-4 -- gobs-O-torque and an awsome sound. Shaft drive though, so you might think about a V drive or better yet a surface drive.
    I do think that you'd be way ahead to use a heat exchanger rather than a rad, why ignore that perfect heat sink you're riding on?
    moT
     
  11. roystr
    Joined: Nov 2006
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    Location: ny

    roystr New Member

    talking about this cooling problem,, as far as the bike engine in a boat.

    i have no expierence with any thing like this. but i have been stewing for a while now,and im stuck

    what problems would i encounter if a put a 3 cyl snowmobile engine into a smallish street bike?
    this has been on my mind for some time,but i have nobody to ask.

    any ideas?
    if so,we can move this to another page.i dont want to be in the way.

    thanx for anything,

    roy
     
  12. MntFisher
    Joined: Apr 2006
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    Location: Hudson Colorado

    MntFisher New Member

    we did this with a harley motor. we did direct drive with a cluth on it from a company called emf. worked great . boat was a 14 flat. only weight around 500lbs. all i did was install a blower to move the air around it. and modified an air cleaner to work. wish I took a bunch of pics, but didn't.
    Chris
     
  13. jimhales
    Joined: Mar 2006
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    Location: canada

    jimhales Junior Member

    Yamaha YZR1

    If you can find a Yamaha YZR1 engine I think you would have all the torque and HP you need. These engines right out of the box are 150 hp and deliver a 300KMH ride on the bike itself with no mods., Not sure where you are from but there is a wrecked one with a very good engine and tranny and extras for around $1500 CDN in the city here. Actually, all kinds of motorcycles come up frequently through this insurance company dispersal auction sight during the summers. Sadly, Lots of kids kill themselves with the thrill of speed on these things.
     

  14. Frosty

    Frosty Previous Member

    Theres a lot of engines could do the job. But its not as simple as that. My choice --a gold wing 4 or 6 was chosen because of its integral gearbox and shaft drive.

    Exhaust are simple straight out of the side and carbs are facing inwards and would be easy to box and keep dry.

    Exit shaft would mean torque is transmitted in the usual way with out wastage, compared to an exit drive of a sprocket on the side which would need some nifty conversion.

    It is from a very heavy bike and therefore I would assume would have torque. Torque is what you need for a boat not HP

    I am not Familiar with the YamahaYZR1 engine but these things need carefull considerations.

    Not having any money as a kid if I wanted something I had to make it.
     
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