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A65 Cylinder Base Studs #32731
01/08/08 12:24 am
01/08/08 12:24 am
Joined: Jan 2008
Posts: 8
G
Gee80-15 Offline OP
BritBike Forum
Gee80-15  Offline OP
BritBike Forum
G

Joined: Jan 2008
Posts: 8
So what year and/or engine number did BSA change from 5/16 to 3/8 inch cylinder base studs on the A65? Any other changes during this period make the later-earlier engines incompatable? I know that the earlier and later head/valve cover are different. Anybody?

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Re: A65 Cylinder Base Studs #32732
01/08/08 1:20 am
01/08/08 1:20 am
Joined: Feb 2004
Posts: 1,956
Flint,Mich
norbsa48503 Offline
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norbsa48503  Offline
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Joined: Feb 2004
Posts: 1,956
Flint,Mich
69's go to 3/8 base studs. 71-72 had a rocker cover that is about 1/2 wider pattern and 5/16 studs as well.


norbsa
1960 TR6
1963 Super Rocket
1965 650 Star
1966 441
1968 Thunderbolt
1969 Twinkle 250
1972 Fastback
1974 Roadster
1970 S.S
Way too many BSA's not named
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Re: A65 Cylinder Base Studs #32733
01/08/08 3:17 pm
01/08/08 3:17 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

BritBike Forum member

Joined: Sep 2002
Posts: 7,813
Seattle
Gee, not only the size, but the location of the two center front studs changed as well. Still, you can put a later barrell on an early set of cases, you just have to do some drilling and put on some nice hardened washers. bigt

The clutch actuation and shifter mechanism changed as well.


A smattering:
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sixtyseventy Lightboltrocket road racer...and many more.
Re: A65 Cylinder Base Studs #32735
01/08/08 7:17 pm
01/08/08 7:17 pm
Joined: Oct 2007
Posts: 1,540
Auckland NZ
Ignoramus Offline
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Ignoramus  Offline
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Joined: Oct 2007
Posts: 1,540
Auckland NZ
the oil pump also changed from die-cast alloy to cast iron (I think 69 but not 100% sure), if using the latter cast iron ones with earlier cases you will need more clearance inside the timming side inner cover, the latter ones had clearance cast in

probably the most majour difrence between the pre66 and latter cases are the arangment for the main crank bush. The machining of the cases is totaly diffrent to accomidate a narrower bush (across the flats), diffrent side thrust arrangment etc


"There's the way it ought to be and there's the way it is" (Sgt Barnes)

Moderated by  Allan Gill, Jon W. Whitley 


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