Newbie - Interesting motor - questions...

Discussion in 'Introduce Yourself' started by Donorbikesdie, Nov 21, 2010.

  1. Donorbikesdie

    Donorbikesdie New Member

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    Hello fellas, my name is Josh. I'm in Australia.


    I figure I fit in here. I've got a daily rider I built myself, the Jalopy. Its a special bike because I'm 6'4 and it needed to be long to fit.

    I have seen loads of those kit motors around...but I have this aversion to anything thats "Off-the-shelf" y'know...No disrespect intended to the guys who have one here...

    So I held out for years, and the Jalopy now has a healthy patina coming through the primer.

    Last weekend I found an air-compressor being given away on a neighbours front lawn. I thought I could use it for work, doing paint on surfboards, my job.

    On inspection I got more excited. The motor is petrol, and a small J.A.P no less!

    J.A.P - John Alfred Prestwich - An English company, made some of the best engines ever in motorcycle history, including a 500cc that reigned speedway racing from the '20's to the 60's. This is the ultimate engine I seek for my "real" motorcycle project someday, someday...

    But for my current resources and mechanical ability, the small J.A.P is a great start.

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    Can anyone say more about this motor ? I found the number 02 embossed in the barrell. Maybe thats the model number. I can't tell what capacity it is.

    Here it is off the compressor tank...

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    JD
     
  2. Donorbikesdie

    Donorbikesdie New Member

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    Here's the Jalopy - Plenty of room there for a motor!

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    And the gas tank I have, from a 60's Jawa speedway motorcycle...

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    Is it possible to have the engine driving through the derailler gears rather than a added sprocket on the other side? Some sort of double sprocket at the pedal cranks end, so that the pedals free-spin when the engine is running?

    JD
     
  3. wheelbender6

    wheelbender6 Active Member

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    I love the arched fuel tank. I'd rack mount that motor so I could show off that cool tank.
     
  4. 2door

    2door Moderator
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    Very interesting project. Good luck and please keep us posted on your build. That should make one heck of a motor bike. Is that a built in centrifugal clutch? Have fun and ride safe.
    Tom
     
  5. Donorbikesdie

    Donorbikesdie New Member

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    Thanks Gents...I'll need o do some more research to find out about the engine.

    I'm so green I can't say whether there's any sort of clutch there. I'm coming at this from out of the dark with actual engine knowledge beyond the theory of internal combustion from high-school science class...and tuning my '68 Chrysler...

    I did however find the answer to my own question regarding using the derailler as the powered side, with the cranks able to free-spin when the engine runs. It is common with "stretch cruiser" bikes I see elsewhere in the forums.

    Torn between the red tank and my Jawa speedway one, which was earmarked for that someday larger bike...The blue one just fits so well.

    I guess I'll be a while, but finding this foprum is a kick for inspiration.

    JD
     
  6. Donorbikesdie

    Donorbikesdie New Member

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    I got somewhere with the engine model research...Its a JAP model 80.

    79cc! That should move me along just fine hey! I was afraid it would be too wimpy as there where other ones as little as 34cc used in outboard boat motors.

    Here's a video -
    <object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/Hx_5nF1qyK4?fs=1&amp;hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/Hx_5nF1qyK4?fs=1&amp;hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>
     
  7. Donorbikesdie

    Donorbikesdie New Member

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    Time for a first basic mock-up. The motor is designed to sit with the cylinder horizonal.

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    I'm thinking straight upright - more conventional old motorcycle look rather than pit-bike style. Sort-of like a Simplex. There might be a way to turn the cylinder barrel around 90deg. so the carby and exhaust are not poking out sideways...

    But I figure I'll do the work on getting it running before I start pulling bits off.

    And lose the red tank - I'm not keen on the way it looks like a chainsaw. So I'm planning to get hold of a welder again to make brackets for the Jawa speedway tank.
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    Want a little gearbox - "Pre-Unit" style.

    I have an alternative seat - undecided...

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    JD
     

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