Carburetor Controls - O.S. engine MaX-37SZ-HRING Manual

With a fixed-wing model, power failure is rarely a
serious threat to the safety of the aircraft since it can
usually glide down to a safe landing. In a helicopter,
on the other hand, it is vitally imporant that the engine
keeps running and that there is a quick and reliable
response to the throttle in order to ensure safe ascent
and descent of the model.
Two adjustable controls are provided on this carburetor.
The Needle Valve:
When set to produce maximum power at full throttle,
this establishes the basic fuel/air mixture strength.
This is then maintained by the carburetor's
automatic mixture control system to cover the
engine's requirements at reduced throttle settings.
The Mixture Control Valve
For adjusting the mixture strength at part-throttle
and idling speeds, to obtain steady idling and
smooth acceleration to medium speeds. The Mixture
Control Valve has been factory set for the
approximate best result. First, run the engine as
received, and re-adjust the Mixture Control Valve
only when necessary.
REALIGNMENT OF MIXTURE CONTROL VALVE
In the course of making carburetor adjustments, it is
just possible that the Mixture Control Valve may be
inadvertently screwed in or out too far and thereby
moved beyond its effective adjustment range.
Its basic setting can be reestablished as follows :
First rotate the Mixture
0.5mm
Control Valve until its
slotted head is flush with
the
Then screw the valve in
exactly 1 turn. This is the
standard position.
Mixture Control Valve
Carburetor Body
18
Fully opened position
As shown in the sketch, the carburetor has graduation
carburetor body.
marks. When the triangle mark on the carburetor rotor
meets the most right mark, throttle is fully closed.
When the triangle mark meets the top mark, throttle is
fully open. The range is approximately 80 degrees. You
may use other three marks as the reference marking of
throttle opening to your preference when hovering.
WARNING!
Never try to check the triangle mark position while
the engine is running and rotor is rotating, or you
may be hit by rotating rotor which results in serious
injury. Stop the engine and rotor before checking
the triangle mark position.
19

CARBURETOR CONTROLS

MIxture Control Valve
Needle Valve
GRADUATIONS ON THE CARBURETOR BODY
Approx.
Fully closed position
Carburetor Body
Carburetor Rotor