O.S. Engines 91SZ-H - Manual (Page 15)

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ADJUSTING CHART
High Speed Needle Valve - 2 turns opened from fully closed position.
Medium Speed Needle Valve - 2 turns opened from fully closed position.
Start the engine
Warm up the engine
Observe the mixture condition while "floating" the model
Turn the Idle Mixture
Control Screw counter-
clockwise 5 degrees
Idling OK
Turn the Idle Mixture
Control Screw
clockwise 5 degrees
Lean mixture Rich mixture
Observe the hovering mixture condition
Open the High Speed
Needle Valve
(Turn counter-clockwise)
Hovering OK
Lean mixture Rich mixture
Close the High Speed
Needle Valve
(Turn clockwise)
Land the model
Idle for approx: 10 seconds, then reopen throttle to
observe transition ("Float" the model)
Idling OK
Lean mixture Rich mixture
High Speed Flight
Lean mixture Rich mixture
High Speed Flight OK
Fine tuning of hovering mixture
Open the Medium
Speed Needle Valve Hovering OK
Adjustment completed
Open the High Speed
Needle Valve
(Turn counter-clockwise) Close the High Speed
Needle Valve
(Turn clockwise)
Fine tuning of idling mixture
Lean mixture Rich mixture
Idling OK
Lean mixture Rich mixture
Close the Medium
Speed Needle Valve
Turn the Idle Mixture
Control Screw
clockwise 5 degrees
Turn the Idle Mixture
Control Screw
clockwise 5 degrees
Turn the Idle Mixture
Control Screw counter-
clockwise 5 degrees
Turn the Idle Mixture
Control Screw counter-
clockwise 5 degrees