| Also known as | W3761 |
| Diagram | Fig. 2 — CRANKCASE · ref 21 |
| Subsystem | engine bottom |
| Listed in parts books | 1971–1974, 1976–1980, 1983, 1985 |
‘O' ring, ignition timing hole plug
The O-ring that seals the ignition timing hole plug on the timing cover, sealing against oil seepage when the plug is removed to check timing.
This is the small O-ring that seals the ignition timing hole plug on the timing cover. Triumph twins use a threaded plug in the timing cover so you can pull it out and line up the timing marks on the flywheel or rotor without cracking the case open. This O-ring sits under that plug to keep oil from seeping out of the hole when the plug's threaded back in.
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It shows up in the catalog under the crankcase, gearbox inner cover, and timing cover figures because the timing hole plug gets referenced from a few different angles in the parts books, but the part itself lives at the timing cover. The older part number for this one is W3761, which you'll see if you're working from an early parts book.
It's a cheap thing to replace and easy to overlook until you notice oil weeping around the timing plug. If you're already popping that plug to check your timing, it's worth having one of these on hand so you're not reusing an old, flattened ring.
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