BSA A7 or Huntmaster? Crankshaft Identification Help Needed

[JimWalker]

Thanks again for any help, This is a Crank labelled as a BSA A7 500cc, its was included in my Huntmasters parts collection that I got included in sale and was thinking it fitted the Huntmaster as it is A10 based internally?

[simon.holyfield]

Tricky to measure accurately, but if it's A7 it's 82 mm stroke and if it's A10/Huntmaster it's 84 (I think)!

As far as I know, most Huntmasters use the small bearing A10 crank; only the very last use the large bearing crank.

[Simon.Gardiner]

By the shape of the webs and having the flywheel bolted on 'internally' with axial bolts I'd say that's not A10!

(Anyone thinking about a short-stroke 600cc Huntmaster maybe?? )

SG

[simon.holyfield]

By the shape of the webs and having the flywheel bolted on 'internally' with axial bolts I'd say that's not A10!

(Anyone thinking about a short-stroke 600cc Huntmaster maybe?? )

SG

Certainly doesn't look like mine!

[robjameson]

Doesn’t look right for huntmaster to me, so most likely what it says on the tin!

[will_curry]

I think it's a small journal A7 or A10. If so the timing side journal will be 1.375"
and the big end 1.46".

I've seen these cranks both with and without the chamfer on the outer edge of
the web. Chamfered cranks will fit either Ariel or BSA and unchamfered cranks
only fit one but I can't remember which.

Big journal cranks - 1.687" - have the flywheel secured with three bolts going in
from the circumference - if I remember correctly.

[fpassmore]

I agree A7, long stroke possibly, you need to measure stroke and journals then it becomes obvious. Sure looks the same as the one I just put in my ‘48 A7 LS.
Frank

[simon.holyfield]

Big journal cranks - 1.687" - have the flywheel secured with three bolts going in
from the circumference - if I remember correctly.

That’s right Will!