O.S. engine MAX-61SX-H RING WC Series Owner's Instruction Manual page 19

Now adjust the High-Speed Needle Valve to
3.
achieve the best performance when the model is
flying at full throttle. lf, at full throttle, acceleration
is poor, the exhaust unduly smoky and the model
fails to reach expected straight line speed, the
mixture is too rich and the High-Speed Needle
Valve setting will need to be reduced.
lf, however, after smoothly acceIerating to
satisfactory high-speed straight and level flight,
power is lost when the model is puIled up into a
climb, the mixture is too lean. ln this case, land the
model immediately and readjust thw High-Speed
Needle Valve to a richer setting.
4. Having now found the optimum setting for the
High-Speed Needle Valve, re-check the engine's
idling performance, finetuning the Idle Mixture
Control Screw, if necessary, to perfect the idle.
Now re-check hovering performance It may be
5.
found that (with the High-Speed Needle Valve
now set for optimum full-throttle performance)
hovering will reveal symptoms of slightly lean
running at medium speeds. DO NOT touch the
High-Speed Needle Valve.
It is at this point that the Medium Speed Needle
Valve, previously kept one turn open, may be
brought into operation. Open the Medium Speed
Needle Valve 45˚, or 4-5 clicks, then fine tune until
the optimum hovering performance is obtained. If
on the other hand, hovering reveals rich running,
close the Medium Speed Needle Valve gradually
until the optimum hovering performance is
obtained.
NOTE: It is NOT necessary to open the Medium
Speed Needle Valve if symptoms of lean running at
hovering speeds remain unconfirmed.
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