| Diagram | Fig. 29 — CARBURETTER, T100S, T100 AND T100C · ref 6 |
| Subsystem | fuel |
| Listed in parts books | 1968, 1970–1974 |
Throttle valve (3 cutaway) (99- 4125)
Amal Concentric throttle valve, cutaway 3, part 622/060 (also listed as 99-4125).
This is the Amal throttle valve, cutaway number 3, for Concentric carburetors — catalog number 622/060, cross-referenced to 99-4125. It's the slide that rides up and down inside the carb body when you twist the throttle, and the cutaway on its leading edge shapes how air and fuel mix as the slide lifts off idle.
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The cutaway number stamped on the slide (in this case a 3) is one of several Amal offered, each cut a little differently to fine-tune the transition off idle before the needle and needle jet take over further up the throttle range. It's a wear part — the slide rides in the carb bore on every throttle movement, so bores and slides both wear over time and a sloppy fit here shows up as poor low-throttle response.
This one turns up across a run of catalog entries for T100-family carburetor setups from 1968 into the mid-'70s, spanning several carburetor figure listings. If you're chasing a specific model fitment, best to have your carb in hand or the original slide out so you can match the cutaway number and confirm bore fit before ordering.
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