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DAMadd #894759 11/04/22 9:29 pm
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You can fit any a65 crank in any set of a65 cases, the variant is the amount of pi$$ing about to do it.
By the time you've messed about line boring a bush you may as well stick a needle race in anyway.
It normally works out cheaper.

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NickL #894981 11/08/22 11:53 pm
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Originally Posted by NickL
You can fit any a65 crank in any set of a65 cases, the variant is the amount of pi$$ing about to do it.
By the time you've messed about line boring a bush you may as well stick a needle race in anyway.
It normally works out cheaper.
A later crank can be fitted in an early ('65) case?


1967 BSA Wasp
1967 BSA Hornet (West Coast Model)
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1965 BSA Cyclone Competition Build
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DAMadd #894999 11/09/22 4:57 am
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Yes.
You just need to make up a couple of thrust washers.

DAMadd #895012 11/09/22 12:16 pm
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Hoping the original crank is good, but I have a backup. I'll have to check it for part number and figure out what year the extra is.
Came with the 68 tbolt parts, which was a complete mish mash. Could be a 70's crank for all I know..


Addendum: extra crank=68-0734
66 to 70 according to Roy Bacon's book so hoping for the 245 miles of wear showing on the speedo from 57 year old machine ( that's humor)

Last edited by DAMadd; 11/09/22 4:02 pm.

Dave
65 TR6R 68A65T 69 B44VS. 74 T150V 65 A65 D L/R
19 Chieftain
NickL #895014 11/09/22 1:53 pm
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Originally Posted by Gary E
A later crank can be fitted in an early ('65) case?
Originally Posted by NickL
Yes.
You just need to make up a couple of thrust washers.
For me, that's just asking for trouble.
The misconception about the "narrow" or "wide" crank is that the entire thing is wider. This is incorrect: only the internals, shoulder-to-shoulder, are wider. The crank as a unit it the same width, tip-to-tip.

What this means is that the later cases are machined on the right side to house a slightly different bush (plus thrust washer) and then the left side face is machined thinner to provide room for the wider counterweights and (this is critical) the bearing lip is machined to shift it to the left, away from the crank.

Once you've gone through the headaches of actually getting a later crank to fit in a narrow case without binding or hitting anywhere, you'll next need to identify the correct spacer(s) to realign the crank sprocket to the clutch chainwheel, the alternator rotor to the stator, etc.

I'm not saying it can't be done, or that is hasn't been done successfully. I just feel it's much more likely to go wrong than right. I personally would never be confident that I didn't get one of the measurements wrong and would feared having the whole thing lock up when warmed up. Much easier to stick with proven parts.

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DAMadd #895038 11/09/22 11:31 pm
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When you ain't got the 'correct' parts', what you have must be made to suit.
I must have done this job 4 or 5 times over the years, the timing side has no captive
thrust washer so one needs making and fitting or a needle race fitted.
Don't use that crap shim pack on the drive side a single thin washer is all that's needed
just make sure the crank is centred.
Setting up the chain alignment is standard practise anyway.
It's not always possible to do things the easy way.

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