| Also known as | E9249 |
| Diagram | Fig. 11 — CHAINCASE AND CHAINS · ref 21 |
| Subsystem | primary |
| Listed in parts books | 1969–1970, 1974 |
PRIMARY COVER T100 68-74
Outer primary chaincase cover for the Triumph T100 unit twin, catalog PN 70-9249 (also listed as E9249).
This is the primary chaincase cover for the T100, Triumph's unit-construction 500 twin, as shown in the catalog for the 68-74 span. It's the outer lid of the primary cover assembly, the piece you see on the left side of the engine that closes off the primary chain, clutch, and alternator from road grime and keeps the oil bath contained. The older parts-book listing carried this part as E9249, so if you're working from an early manual or a bike with a legacy tag on the box, that's the same physical cover under the current number 70-9249.
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It sits in the CHAINCASE AND CHAINS section of the parts books, which tells you it's part of that whole chaincase assembly rather than a standalone cosmetic piece — expect it to mate up with the inner cover, gaskets, and fasteners that seal the primary drive.
Given how the catalog ties this specifically to the T100 line, don't swap it onto a different displacement Triumph without checking your own primary case first — cases and covers in this family aren't all interchangeable across the model range, and our records here only speak to the T100 fitment shown.
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