Author Topic: late a7 engine into early plunger frame with gearbox  (Read 634 times)

Offline lizzycombat

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im building a bit of special a7. the frame is a 1951 plunger with matching gearbox. i have later crankcases wthout the gearbox mount. can they be brought together or what options do i have except for sourcing the right bottom end. also can a 5x16" rear wheel fit in the plunger frame
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Offline wilko

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Re: late a7 engine into early plunger frame with gearbox
« Reply #1 on: 27.01. 2015 22:37 »
Hmmm.. a special ***

edited
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beezermacc

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Re: late a7 engine into early plunger frame with gearbox
« Reply #2 on: 27.01. 2015 22:37 »
A set of plunger crankcases wouldn't be very expensive then most of the internals are the same. Similarly you will pay less for a plunger gearbox than a swinging arm type. To be honest I can't see the point of putting anything other than a plunger engine in a plunger frame unless you do something exotic like a Kawasaki Z1... Regarding the wheel, I'm not sure about that, providing you can line the rim behind the front wheel and get the sprocket to line up as well you could be in business but I think you'd need to try the parts in a dry run before committing.
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Offline muskrat

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Re: late a7 engine into early plunger frame with gearbox
« Reply #3 on: 28.01. 2015 00:21 »
G'day lizzycombat  *welcome*.
Yep you'll need the plunger cases, A7 or A10 are the same, most later bits bolt on. Any bigger than a 4.25" will rub the chain guard, with it removed a 5" should fit.
Now get over to Bikes Pictures & Members to say hello and tell us your plans.
Cheers
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline lizzycombat

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Re: late a7 engine into early plunger frame with gearbox
« Reply #4 on: 28.01. 2015 08:22 »
is there anyone out there with plunger a7 crankcases for sale. get in touch
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Offline duTch

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Re: late a7 engine into early plunger frame with gearbox
« Reply #5 on: 28.01. 2015 09:23 »

  Hiya Lizzy- best shot is take Muskies advice and the universe may provide.... *bright idea*
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Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

beezermacc

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Re: late a7 engine into early plunger frame with gearbox
« Reply #6 on: 28.01. 2015 19:29 »
is there anyone out there with plunger a7 crankcases for sale. get in touch

Yep! Give me a ring, contact details via my website, Priory Magnetos Ltd. Hope I can help.
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Offline lizzycombat

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Re: late a7 engine into early plunger frame with gearbox
« Reply #7 on: 28.01. 2015 21:35 »
hi,

thanks for getting back to me. have you some crankcases i could use. its been a bit of a learning curve i assumed all the a7 and a10 bits were
interchangeable so i have a few bits to sell on.
mod edit: please use PM or email.
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Offline colr6

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Re: late a7 engine into early plunger frame with gearbox
« Reply #8 on: 30.01. 2015 16:52 »
Hi, I have 48 plunger. Used later plunger cases and gearbox then put all shooting star top end on it including camshaft.Had to cut and modify inlet manifold so could use mono bloc carb and original air box (to keep things looking tidy) had to put top end of engine on when lower half in frame because it won't go in complete. Used plunger exhausts with a bit of tweeking. Does not out of place because no-one at the shows have spotted the conversion. All in all it goes and sounds well  regards Colin
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Offline muskrat

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Re: late a7 engine into early plunger frame with gearbox
« Reply #9 on: 30.01. 2015 19:01 »
G'day colr6. That sounds like a bit of work that paid off. I too have an SS top end sitting on the '51 bottom end.
Cheers
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7