??? - crankshaft bush to bearing on the A65?

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not sure i'm even on the right track here - question - (if they did at all) - what year on the A65 engine did BSA go from a bush, or bushing, to a bearing on the timing side crankshaft? TIA....
 
As long as the bushing is not worn you don’t need to worry given two things. Add an oil filter and change the oil regularly.
 
If you suspect wear on the bushing pull the motor apart and replace the bushing. I believe it should be reamed in place to match the crankshaft (with correct clearance). Then ride the bike until all the other parts fall off.
 
As stated, they never went to a bearing (on production bikes anyway). The conversion can be a contentious topic, but it really just comes down to how you plan to ride the bike.

For:

Against:
 
The bush is at the smallest size acceptable, just at the limit for the loads so needs everything else to be at top limits. Hence as soon as the bush wears beyond 2 thou clearance the oil pressure drops and the wear rapidly increases. Hence the need for line reaming and the 1.5 thou starting clearance. The fix developed by Devimead (later taken over by SRM) who raced A65 sidecar outfits was to swap the bush for a combined needle roller/ball bearing. However because of space limitations even this is marginal and prone to wear but at a lower rate and the big ends still got oil. Later DIY versions use a full width needle roller bearing which increases the load capacity plus an outrigger plate with a ball bearing on the alternator side to stop the crank from moving side to side.
 
thanks for all the replies. no experience with the A65 or BSA's in general, so somewhat of a noob. going tomorrow to look at a 66 spitfire - trying to gather a little background and information on the brand in general. again, thanks....
 
A well sorted A65 is hella fun to ride IMO, nice free revving motor
 
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