O.S. Engines 21VZ-B V-Spec - Manual (Page 30)

Incorrect carburetor fitting Fit carburetor securely.
Incorrect setting of transmitter Exponential function.
Too much throttle opening at idling.
Poor r.p.m. drop
Check the transmitter setting.
Close metering needle to adequate position
to lower idling r.p.m.
Readjust low r.p.m. range with metering
needle and mixture control valve.
Replace glowplug. Deteriorated glowplug
Incorrect carburetor settings
Poor response
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