Newbie - Interesting motor - questions...

GoldenMotor.com

Donorbikesdie

New Member
Nov 21, 2010
5
0
0
Victoria Australia
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
 

Donorbikesdie

New Member
Nov 21, 2010
5
0
0
Victoria Australia
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
 

wheelbender6

Well-Known Member
Sep 4, 2008
4,059
221
63
TX
I love the arched fuel tank. I'd rack mount that motor so I could show off that cool tank.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
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
 

Donorbikesdie

New Member
Nov 21, 2010
5
0
0
Victoria Australia
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
 

Donorbikesdie

New Member
Nov 21, 2010
5
0
0
Victoria Australia
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>
 

Donorbikesdie

New Member
Nov 21, 2010
5
0
0
Victoria Australia
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