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Alloy JAP Mark 2 v - twin engine #345654
11/29/10 8:12 pm
11/29/10 8:12 pm
Joined: Nov 2010
Posts: 39
east midlands, england
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mwebb Offline OP
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east midlands, england
I have been asked by a friend if I know when the JAP Mark 2 alloy v -twin engine first appeared, does anybody know?

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Re: Alloy JAP Mark 2 v - twin engine [Re: ] #346528
12/04/10 9:45 pm
12/04/10 9:45 pm
Joined: Nov 2010
Posts: 39
east midlands, england
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mwebb Offline OP
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Cameron engineering do make some replica jap parts but are not a total authority on the history of the company, sadly i dont think anybody really is, when the company closed its doors much of their history was lost.

Re: Alloy JAP Mark 2 v - twin engine [Re: ] #346606
12/05/10 1:10 pm
12/05/10 1:10 pm
Joined: Oct 2007
Posts: 727
bromley uk
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norton bob Offline
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bromley uk
These motors were orriginaly used in the superbikes of the era, the new build motors were for reborn Brough Superior Replicas and spares for the now astronomically valuable vintage bikes.

Re: Alloy JAP Mark 2 v - twin engine [Re: norton bob] #346671
12/05/10 9:30 pm
12/05/10 9:30 pm
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east midlands, england
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mwebb Offline OP
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"Yes" some of the original jap v - twin engines where fitted in Brough Superior motorcycles.These pre war engines featured cast iron cylinder heads & barrels with aluminium crankcases, but as far as we can tell the so called JAP Mark 2 engines were produced after the second world war,they had aluminium cylinder heads & barrels with magnesium crankcases.
The question is from what date did production start and now another question is what was the intended use?
Any ideas?

Re: Alloy JAP Mark 2 v - twin engine [Re: ] #346901
12/07/10 8:40 am
12/07/10 8:40 am
Joined: Oct 2007
Posts: 727
bromley uk
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norton bob Offline
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bromley uk
In the Uk speedway bikes were 500cc dope burners,Australian speedway used big motors,Morgan trikes used big vees.

Re: Alloy JAP Mark 2 v - twin engine [Re: norton bob] #346914
12/07/10 1:05 pm
12/07/10 1:05 pm
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east midlands, england
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mwebb Offline OP
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The alloy JAP mark 2 engines were 1100cc 50 degree v - twins, I think they may be a little big for a speedway bike?

The driveside crankcase casting half has an integral ring built onto the crankcase casting which may have been used for the fitting a bell housing?

Last edited by mwebb; 12/07/10 5:59 pm.
Re: Alloy JAP Mark 2 v - twin engine [Re: ] #346980
12/07/10 8:09 pm
12/07/10 8:09 pm
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Posts: 39
east midlands, england
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mwebb Offline OP
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Nice picture!

With regards to the engine / model number, I cant say that I have ever seen an engine / model number being quoted.

Everybody just refers to them as "Mark 2 engines"!

Unless you know better?

Re: Alloy JAP Mark 2 v - twin engine [Re: mwebb] #347000
12/07/10 11:02 pm
12/07/10 11:02 pm
Joined: Apr 2006
Posts: 1,406
New Zealand
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johnm Offline
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New Zealand
Greg might be able to help

http://www.eurospares.com/greg.html

He comes on here occasionally but got beaten up about stress calculations last time so not often about.

John

Re: Alloy JAP Mark 2 v - twin engine [Re: mwebb] #347096
12/08/10 3:24 pm
12/08/10 3:24 pm
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Posts: 727
bromley uk
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norton bob Offline
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bromley uk
The Australians used Vincent and other vees in their sidecar dirt track racers.Post-war this type of motor is regarded as outdated vintage curiosities and are not likely to feature in any mass produced product.Thats not to say that the sort of power they make would not make a great bike to ride,I'm building a 900cc vee twin with a puny 60 bhp (in comparison with todays products) that will be perfect for me.

Last edited by norton bob; 12/08/10 3:31 pm.
Re: Alloy JAP Mark 2 v - twin engine [Re: ] #347246
12/09/10 9:36 am
12/09/10 9:36 am
Joined: Oct 2007
Posts: 727
bromley uk
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norton bob Offline
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bromley uk
A number of clever engineers have produced similar creations over the years ,usually for competition use,but without a neat alternator,ignition and oil pump set-up they just don't make good road bikes ,which is a real shame.My 900 Ducati bevel will tick all my boxes.

Re: Alloy JAP Mark 2 v - twin engine [Re: norton bob] #347463
12/10/10 10:21 pm
12/10/10 10:21 pm
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Posts: 39
east midlands, england
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mwebb Offline OP
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east midlands, england
I have now been informed that these so called "Mark 2" JAP engines might not be "Mark 2" engines after all!
My contact, Paul at MFC Patterns & Castings has now informed me that they have JAP general arrangement drawings showing two versions of the engine, one with the ring for the bell housing and another version without the ring on the driveside half.
The strange thing is that the drawings are titled "Mark 1" (minus the ring) and "Mark 1" type 2 (with the ring)!

Re: Alloy JAP Mark 2 v - twin engine [Re: mwebb] #348014
12/14/10 8:16 pm
12/14/10 8:16 pm
Joined: Nov 2010
Posts: 39
east midlands, england
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mwebb Offline OP
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My final conclusions on the subject, for what they are worth!

The alloy JAP 1100cc engine was available from 1949 onwards and was intended for use in racing cars, it should be known as a "Mark 1 - Type 1" or "Mark 1 - Type 2".

It developed around 95 bhp on racing fuel at 5500 rpm, or using petrol around 60 bhp.

Engine weight 125lb, retail cost was 195.00.

Case closed.


Re: Alloy JAP Mark 2 v - twin engine [Re: mwebb] #409628
12/20/11 11:11 pm
12/20/11 11:11 pm
Joined: Oct 2004
Posts: 112
Adelaide South Australia
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Adelaide South Australia
" have now been informed that these so called "Mark 2" JAP engines might not be "Mark 2" engines after all!
My contact, Paul at MFC Patterns & Castings has now informed me that they have JAP general arrangement drawings showing two versions of the engine, one with the ring for the bell housing and another version without the ring on the driveside half.
The strange thing is that the drawings are titled "Mark 1" (minus the ring) and "Mark 1" type 2 (with the ring)!"


I'm afraid this is not quite correct, I have a copy of a JAP factory drawing (number 1506) that is marked "General Arrangement of OHV Twin Mark 1 engines Type 1" that clearly shows the ring for the bell housing. I also have a drawing marked number 1505 that shows the same cases but without the ring...however this engine has the older cast iron model 8/80 heads and cylinders and is marked "Model 8/80 OHV twin - Dry Sump" . The heads and cylinders are the same as those shown in JAP factory drawing 1362 that is of the model 8/80.

I believe the Mark 2 moniker may have been sort of "transferred" from the model number of the new Cooper car that the new big fin alloy engines of 1949/50 were primarily developed for that also appeared in 1950. I think the car model name sort of got transferred to the JAP engine and totally ignored the fact that JAP called their engines "Mark 1"
Does anyone disagree or have any more info on this?
Cheers,
Greg
Greg Summerton
http://www.eurospares.com/greg.html
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Phone: +61 (0)8 82639018
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