| Diagram | Fig. 5 — CRANKCASE · ref 13 |
| Subsystem | engine bottom |
| Listed in parts books | 1970 |
BSA Stud barrel to crankcase (5/16" Unified Fine/Unified Coarse × 1-7/16")
A 5/16 in. barrel-to-crankcase stud, 1-7/16 in. long, with Unified Fine/Unified Coarse threading, from the CRANKCASE figure.
This is a barrel-to-crankcase stud, listed at 5/16 inch with Unified Fine and Unified Coarse threading and a length of 1-7/16 inches. It's one of the fasteners that clamps the cylinder barrel down onto the crankcase mouth, so it sees the clamping load between those two castings whenever the head and barrel are torqued down.
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The catalog record shows this stud under the BSA heading and ties it to the CRANKCASE figure, with a single appearance logged for the 1970 model year. Our records don't spell out which specific model it belongs to beyond that, so if you're matching studs for a rebuild, check the length and thread against what's actually in your cases before you order a set.
If you're replacing one, it's worth pulling and inspecting the rest of the barrel studs at the same time - a stud with damaged threads or a stripped case boss is a lot easier to sort out with the barrel already off.
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