| Also known as | 622/056 |
| Diagram | Fig. 30 — CARBURETTER, T90, T100S AND T100C · ref 7 |
| Subsystem | fuel |
| Listed in parts books | 1969–1970, 1975 |
Throttle return spring (copper plated)
Copper-plated throttle return spring for Amal carburetors on Triumph unit twins, closes the slide when you release the throttle.
This is the throttle return spring that lives inside the Amal carburetor body on Triumph unit twins, the spring that pulls the slide back down and closes the throttle whenever you let off the twistgrip. It's a small but important piece of hardware — if it goes soft, breaks, or gets left out during a carb rebuild, the throttle can hang open or feel lazy coming back to idle.
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Our catalog record shows it appearing in the carburetor sections for the T90, T100S, T100C, T100T, and T100R model families, and it's a common part across Amal carb setups from that era generally. It's described as copper plated, which is the finish you'll see on the part when it comes out of the box or off a good used carb.
The part number 99-0509 was later carried forward as 622/056 — same physical spring, just a different catalog number depending on which parts book or supplier list you're working from. If you're rebuilding a carb and see either number, you're looking at the same item.
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