| Also known as | S1872 |
| Diagram | Fig. 2 — CRANKCASE · ref 24 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1974, 1976–1980, 1983, 1985 |
Plug, timing hole
Threaded plug that seals the crankcase timing inspection hole on Triumph twins.
This is the timing hole plug, 21-1872, the small threaded plug that seals the inspection hole in the crankcase used for checking and setting ignition timing. It shows up across a run of catalog figures covering the crankcase, oil filter and feed pipes, oil and breather pipes, and the gear/selector mechanism, which tells you it's a crankcase-area fastener rather than anything internal to those systems.
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The older book form of this part is S1872, so if you're working from an early parts list and see that number, it's the same plug. It's a simple item, but it's one of those small parts that's easy to lose track of when the engine's apart, and worth having on hand rather than reusing a buggered one.
Our records show it appearing steadily across catalog listings from 1969 into the mid-1980s, which points to a long production run, though we'd confirm exact fitment against your own parts book before ordering.
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