Author Topic: primary cases  (Read 828 times)

Offline wilko

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primary cases
« on: 22.07. 2014 08:13 »
Anyone here have a set of swinging arm primary cases for a single and a set for twins for comparison? A friend needs a set for a B33 but the twin ones are more common. Just want to see if a sleeve arrangement could be made up to suit the single engine cases?

Offline Beezageezauk

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Re: primary cases
« Reply #1 on: 22.07. 2014 09:41 »
Hi Wilko,

One of the main differences is that the alloy inner primary case for the "B" series has a cut-out cast into the top of it.  This cut-out gives clearance to fit the magneto end cap.

Because of this your friend wouldn't be able to substitute a "B" series case with an "A" series one without some serious reconstruction.

Beezageezauk.

Offline wilko

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Re: primary cases
« Reply #2 on: 22.07. 2014 23:56 »
So I guess the chain line sits out further on a twin ?

Online chaterlea25

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Re: primary cases
« Reply #3 on: 23.07. 2014 00:11 »
Hi Wilko,
The singles have a boss at the crank endas part of the inner case to space it out further than a twin case
but the twin case has a spacer to do much the same job
The single models have the chain 1/8 - 3/16ths further in than a twin
The reason for the cut out on the singles is to access the points on the magdyno
The outer covers are the same, thats why theres a thick section at the top of the outer case

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Topdad

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Re: primary cases
« Reply #4 on: 23.07. 2014 14:31 »
thats really interesting ,abit of info to be stored away, cheers john, BobH
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Offline wilko

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Re: primary cases
« Reply #5 on: 24.07. 2014 00:07 »
I'm not giving up on the idea until I have one in my hand. Seems like a machined alloy sleeve could be made after all to make up for the raised boss at the back. 

Online chaterlea25

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Re: primary cases
« Reply #6 on: 25.07. 2014 00:34 »
Hi Wilko,
Yes I have seen that done, Its a bit more difficult to incorporate the cut away portion for the magdyno
A set sold like that recently on fleabay

John
1961 Super Rocket
1963 RGS (ongoing)