| Also known as | S1920 |
| Diagram | Fig. 2 — CRANKCASE · ref 8 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1970, 1974 |
SCREW 1/4 UNC ALT LEAD
A 1/4 UNC screw used in the primary chaincase assembly, listed as an alternate lead screw for 1973.
This is a 1/4 UNC screw listed under part number 21-1920, showing up in the chaincase and chains section of the parts book for 1973. It's a fastener used in the primary chaincase assembly, the enclosure that houses the primary drive chain between the engine and gearbox.
Read more
The catalog notes it as an alternate lead screw, which tells us there was more than one screw spec used for this fitment position depending on the build. If you're replacing chaincase hardware, it's worth matching up what's actually on the bike before ordering, since chaincase screws can vary by year and assembly.
We don't have a lot more detail on this one beyond the thread spec and where it sits in the book. Give us a call if you want to confirm it's the right screw for your chaincase before you order.
Sorry if we got something wrong here. If you think this information isn't correct, .