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B31/B33/34/M33

These overhead valve machines (with iron cylinder and iron head) were made between 1946 and 1962. Rigid frames, plunger and swinging arm.
Many parts interchange with 2 cylinder A7 and A10 and M20 and M21 sidevalves and Gold Stars. If you can't find it here, type an original part number in the finder...
The swinging arm models use the STD gearbox
The rigid frame bikes share the gearbox with M20

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INLETRUBBER

42-4568
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bsa42str4568rubberb31
Inletrubber for B31 and B33 swinging arm models (1954>)

OIL LINE

65-1218
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Return line on B31 and B33 in plungerframes.

REAR BRAKE SHOES

65-5901
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Fit most  B31-A10 models 180 x 28mm

BRAKE DRUM

65-6294
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Brake drum and sprocket for B31/33 plungerframe. Narrow sprocket, 5/8 x 1/4", 42T. Quickly detachable, large centre hole.
Bolts: 67-3038

OIL LINES PLUNGER SINGLES/TWINS

BSA892
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Oil lines for the plungerframe singles and twins
Includes BSA# 65-8420, 65-8424, 65-8465.