A7 Plunger Star Twin '52 cylinder\head\crank

[Richard A]

Hi, can anyone help I am looking for a standard A7 cylinder block (part no 67-378) and cylinder head (part no 67-524) as I'm trying to get my Star twin back to standard spec and when purchased I did not realise that some helpful person had put A10 parts on!

Guess I will find more disasters when I pull it apart, but at the moment running ok.

Thanks

Richard

[Klaus]

Hi Richard,

if an A10 barrel was fit on A7 crankcases you can be sure, there was also an A10 crank inside.
A7 crank has another strocke, so the A7 barrel is shorter with 7 fins, the A10 was 8 fins.
It makes no sens to get an A7 barrel without the right crank.

cheers Klaus

[Rocket Racer]

Like Klaus, not wishing to rain on your parade, your intention to return it to a 500 very noble... but if it happens to have a LJ crank in it why would you want to take that out. Quite a nice option that would make it look like a 500 would be to fit A65 rods which allows the barrel to be milled shorter by 1/2" so has the same number of fins as a 500, but still a 650 
Just a thought.
Tim

[Richard A]

Gents,

Many thanks for your helpful comments and yes I've now managed to measure the stroke and it matches an A10 at 84mm so seems I have the head, barrel and crank of a swing arm A10.
The idea of the A65 conrods does appeal so I will look into that over the winter.

Richard

[Rocket Racer]

A nice thing about a65 rods is the later ones (also used on the A70) were alloy with steel caps, so hold oil pressure better!
There is a bit of work required in shortening the barrels, I think I posted a copy of an article "what makes that beezer go" on how to do it on my racing sidecar thread as my A10 "looks" like an A7 as its shorter!
http://www.a7a10.net/forum/index.php?topic=1998.75

[muskrat]

Started a new topic Con rod length. http://www.a7a10.net/forum/index.php?topic=11056.0
Cheers