O.S. Engines 21XZ-R - Manual (Page 12)

22
Needle
The position of the needle-valve
when starting the engine.
Close the needle-valve approx.
15˚ after running the vehicle for
1 to 2 full tanks of fuel.
Repeat this procedure until
approx. 2 liters of fuel have
been consumed.
Note:
In the event of any major working parts
(e.g. piston/cylinder liner assembly) being
replaced or the fuel being changed,
especially to high nitro fuel, the complete
running-in should be repeated.
Warning!
Do not touch rotating parts, engine and si-
lencer when stopping the engine as they
become very hot, and contact with them
may result in a serious burn.
To stop the engine, close the throttle to idle
speed and shut it off completely with the trim
lever on the transmitter then cut off the fuel
supply by pinching the fuel delivery tube to
the carburetor.
Fuel
How to stop the engine
23
FINAL ADJUSTMENT
Throttle
Stop Screw Needle Valve
Metering
Needle
Open Close Close Open
Needle Valve Metering Needle
More fuel Less fuel More fuel Less fuel
Run the vehicle (with throttle fully open) over
the longest available straight course, in order
to observe the model's speed. Next return
the car to the starting point, close the Needle-
Valve 10-15˚ and repeat the run, taking note
of the improvement in performance.
Continue with further runs, gradually
reducing the Needle-Valve setting and
aiming to achieve the highest straight-line
speed. Remember, however, that, if the
Needle-Valve is shut down too far, the
engine will overheat and, accompanied by
visibly diminished exhaust smoke, the model
will lose speed. At this point, throttle down
immediately, stop the vehicle and reopen the
Needle-Valve 30˚.
Final adjustment should be carried out only after
the running-in has been completed.