O.S. Engines 21VZ-B - Manual (Page 7)

12
LONG SOCKET WRENCH
Recommended for easy removal
and replacement of the angled
and recessed glowplug, the
O.S.Long Socket Wrench
incorporates a special grip.
SILICONE FUEL LINE
Heatproof silicone tubing of
approx. 5mm o.d. and 2mm i.d.
is required for the connection
between the fuel tank and
engine.
CARBURETOR CONTROLS
The Needle-Valve:
The Mixture Control Screw:
Four adjustable controls are provided on this
carburetor.
For adjusting the mixture strength when the throttle
is fully open.
For changing the feeling at mid speads and
acceleration. (Do not rotate the screw more chan
one turn.)
The Throttle Stop Screw:
For setting the minimum idling speed:
For adjusting the mixture strength at part-throttle
and idling speeds, to obtain steady idling and
smooth acceleration to mid speeds.
Needle Valve
Mixture Control Valve
Assembly Screw
Throttle Stop Screw
NOTE: Readjustment may be necessary,
occasionally to allow for changes in fuel formula
gear ratio or clutch engagement point.
The Metering Needle:
Metering Needle
13
•
•
•
Use the same fuel as is to be employed for all initial
running and containing NOT LESS THAN 18%
lubricant.
STARTING THE ENGINE & RUNNING-IN ('Breaking-in')
The following procedure is suitable for these engines
when the O.S. T-2050 tuned silencer and a fuel
containing up to 30% nitromethane are used.
For long life and high performance, every engine
needs to be 'run-in' or 'broken-in'. With care, running-
in of the MAX-21VZ-B(P) can be carried out with it
installed in the vehicle. Be sure to fit the air-cleaner to
the carburetor and to use a muffler-pressurized fuel
system.
Temporarily remove the glowplug to check that it
glows bright red when energized.
Open the Needle-Valve 3 turns from the fully closed
position.
Switch on the transmitter and receiver and set the
throttle very slightly opened from the idling position
(see sketch, top right).
DO NOT energize glowplug, but apply electric
starter to draw fuel to carburetor.
•
•
Now connect glowplug
battery lead to heat the
plug filament and start
the engine. •
Open
Close Needle Valve
Glowplug Heater