O.S. Engines 18TZ(S)-T - Manual (Page 14)

CARBURETOR CONTROLS (11L)
Needle Valve
Throttle Stop
Screw Mixture Control Valve
Thermo Insulator
Three adjustable controls are provided on
this carburetor.
The Needle-Valve:
For adjusting the mixture strength when the
throttle is fully open.
The Mixture Control Screw:
For adjusting the mixture strength at part-
throttle and idling speeds, to obtain steady
idling and smooth acceleration to mid
speeds.
The Throttle Stop Screw:
For setting the minimum idling speed:
NOTE: Readjustment may be necessary,
occasionally to allow for changes in fuel
formula, gear ratio or clutch engagement
point.
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