BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: Caulky on 19 March, 2017, 16:17:56

Title: 1971 A65L plain main bush
Post by: Caulky on 19 March, 2017, 16:17:56
I have two choices,
 1) use the old bush that is already fitted or
 2) fit a new one.

1) The journal is half a thou undersize giving .001" clearance with the bush. (top limit?)
According to the book a re-grind is neccessary when the journal is more than  .002" under.

2) Remove the old bush assy. and fit a new one.
How much would a new crush after fitting?
It may need machining.
What about alignment with the opposite roller bearing?

Any recommendations?

Regards
Caulky

 
Title: Re: 1971 A65L plain main bush
Post by: Bess on 19 March, 2017, 16:44:16
Hi Caulky,
                If it is within specification and undamaged leave it. The roller bearing alignment should be fine unless the crank journal on the drive side is under tolerance, sleeving or the use of loctite should solve that. 

Clean the sludge trap, reassemble and rotate the crankshaft, if it does not rotate freely you have an issue that will need investigation.

Best wishes.....