User Manual
30
IDLING ADJUSTMENT CHART
Start the engine.
Make sure that the throttle is
fully open.
Adjust the needle-valve.
Close the throttle gradually.
Set the idle speed
Open the throttle fully.
Does the engine
regain full power?
Continue running at high speed
for 10 seconds.
Close the throttle.
Run at idle speed for 5 seconds.
Does the engine stop?
Apply full throttle.
Does the engine
regain full power immediately?
OK
Refer to the next section.
Re-set the idle speed at
a little higher r.p.m.
Set the throttle opening by 
means of the throttle trim on
the transmitter so that the lowest
practical speed, without risk of
the engine stopping,is obtained.
The position where the lowest
possible r.p.m. ,with steady 
running, is obtained.
20-45 open from maximum
r.p.m. setting.
Yes.
No.
Yes.
Engine stops.
Engine stops.
Disconnect the battery
leads at mid speed.
Engine stops.
31
MIXTURE CONTROL VALVE ADJUSTMENT
With the engine running, close the throttle and 
allow it to idle for about five seconds, then 
open  the throttle fully. If, at this point, the 
engine is slow to pick up and produces an 
excess  of  exhaust  smoke,  the  mixture  is  too 
rich.  Correct  this  condition  by  turning  the 
Mixture  Control  Screw  clockwise  15-30 
degrees.  If  the  mixture  is  excessively  rich, 
engine rpm will become unstable: opening the 
throttle will produce a great deal of smoke and 
rpm may  drop  suddenly or the engine may 
stop.  This  condition  may  also  be  initiated  by 
excessively prolonged idling. If,on the other 
hand,  the  mixture  is  too  lean,  this  will  be 
indicated  by  a  marked  lack  of  exhaust  smoke 
and a tendency for the engine to cut out when 
the throttle is opened. 
Note: Mixture Control Valve adjustments 
should  be  made  in  steps  of    15-30˚ 
initially, carefully checking the effect, 
on  throttle response,  of each  small 
adjustment.
In  this case,  turn the  Mixture Control  Screw 
counter-clockwise  90  degrees  to  positively 
enrich the idle mixture, then turn the screw 
clockwise gradually until the engine regains full 
power  cleanly  when  the  throttle  is  reopened. 
Carry  out  adjustments  patiently  until  the 
engine  responds  quickly  and  positively  to  the 
throttle control.










