1. Air valve suction (bell) chamber
2. Air valve (piston)
3. Air valve (piston) spring
4. Air chamber to manifold vacuum connection (air less than atmospheric pressure)
5. Suction chamber air inlet (air at atmospheric pressure)
6. Dashpot
7. Dashpot piston damper assembly
8. Fuel needle
9. Jet
10. Jet retaining nut
11. Fuel bowl
12. Carburettor body
13. Throttle butterfly
14. Throttle lever (not shown)
15. Fuel float & fuel supply regulating needle (not shown)
16. Idle speed adjusting screw (not shown)
17. Choke cable (not shown)
18. Choke lever lowers jet to enrich mixture (not shown)
19. Choke cam - slightly opens throttle butterfly so not to starve engine of air when choke is used (not shown)
20. Choke return spring - ensures jet remains in the normal running position – choke is inactivate when engine is warm (not shown). http://www.zparts.com/zptech/articles/mal_land/ml_sucarb2/images4/SUcarb_111601d.htm