| Also known as | 70-5450, E5446 |
| Diagram | Fig. 1 — CRANKSHAFT AND CONNECTING RODS · ref 20 |
| Subsystem | engine bottom |
| Listed in parts books | 1964–1965, 1967–1968, 1970 |
ENGINE SPROCKET 650 29T DUPLEX - NON ET IGNITION (No spot for locating dowel) 70-4572 - NEW PRODUCTION ANDOVER NORTON
29-tooth duplex engine sprocket for the 650 unit Triumph twin, non-ET ignition version with no locating dowel spot.
This is the engine sprocket for the 650 unit-construction Triumph twin, a 29-tooth duplex sprocket that mounts on the crankshaft and drives the primary chain back to the clutch and gearbox. It's the non-ET ignition version, meaning it's cut without the spot for the locating dowel used on the earlier magneto or ET-ignition timing setup, so keep that in mind when you're matching it up against what's already on your crank.
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The part also carries the alias 70-4572 in older parts book listings, and shows up in our records under 70-5450 and E5446 as well - all the same physical piece across different catalog numbering. It lives in the crankshaft and connecting rod section of the parts books, right where you'd expect for a component keyed to the crank end.
This one is noted as new production, sourced through Andover Norton's remanufacturing of Triumph parts, so it's a currently-made replacement rather than N.O.S. stock. If you're rebuilding the bottom end, it's worth checking your existing sprocket for the dowel spot before ordering to make sure you get the version that matches your ignition setup.
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