| Also known as | S1940 |
| Diagram | Fig. 23 — OIL COOLER GROUP · ref 4 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1974 |
Reflector screw (4BA x 9/16 in.)
A 4BA x 9/16 in. reflector mounting screw used in the oil cooler group.
This is a small screw used to mount a reflector on the oil cooler group, catalog number 21-1940, also listed as S1940 in older parts books. It's a 4BA thread, 9/16 in. long, the kind of hardware that's easy to lose track of when a cooler assembly comes apart for service.
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It turns up in the oil tank and cooler figures across catalog listings running from 1969 to 1974, so it's tied to bikes fitted with that oil cooler setup. If you're reassembling an oil cooler bracket and the reflector screw is missing or buggered, this is the one to replace it with.
It's cheap enough to keep a couple on hand in the parts drawer, since a 4BA screw this size isn't something you'll find at the corner hardware store.
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