| Listed in parts books | Not catalogued by year yet |
ENGINE SPROCKET 21T
A 21-tooth engine sprocket that drives the primary chain off the transmission mainshaft.
This is a 21-tooth engine sprocket, part number 70-3108/21. It's the sprocket that mounts on the transmission mainshaft or engine output shaft and drives the primary chain back to the clutch. Tooth count matters here because it's one half of the primary drive ratio, so swapping tooth counts changes gearing.
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Our records on this one are thin — we don't have much beyond the basic catalog listing, no figure title or fitment notes to lean on. If you're trying to match this to a specific gearbox or clutch setup, give us a call and we'll work through it with you before you order.
The /21 suffix on the part number is just the tooth count tagged onto the base sprocket part number, which is common practice in these parts books when the same sprocket casting comes in different tooth counts.
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