O.S. Engines 25XZ - Manual (Page 14)

26
Finally, beyond the nominal break-in period,
a slight readjustment toward a leaner needle
setting may be required to maintain
maximum performance.
CARBURETOR CLEANLINESS
The correct functioning of the carburetor
depends on its small fuel orifices remaining
clear.
REALIGNMENT OF METERING NEEDLE AND
MIXTURE CONTROL VALVE
Mixture Control Valve
Carburetor Body
First rotate the Mixture Control
Valve until its slotted head is
flush with the carburetor body.
This is the standard position.
In the course of making carburetor
adjustments, it is just possible that the
Metering Needle and the Mixture Control
Valve may be inadvertently screwed in or out
too far and thereby moved beyond its
effective adjustment range. The basic
positions can be found by rotating the
Metering Needle until its slotted head is flush
with the ball link body.
Slide Valve
Carburetor Body
Metering Needle
Ball Link
Rotate the Metering Needle
until its slotted head is flush
with the ball link body.
This is the basic position.
27
CARE AND MAINTENANCE
1.
2.
3. The minute particles of foreign matter, that
are present in any fuel may, by accumulating
and partially obstructing fuel flow, cause
engine performance to become erratic and
unreliable.
O.S. 'Super-Filters' (large and small) are
available, as optional extras, to deal with this
problem.
One of these filters installed to the pickup
tube inside your refueling container, will
prevent the entry of foreign material into the
fuel tank. It is also recommended that a good
in-line filter be installed between the tank and
carburetor.
Do not forget to clean the filters regularly to
remove dirt and lint that accumulate on the
filter screens. Also, clean the carburetor itself
occasionally.
At the end of each operating session, drain out
any fuel that may remain in the fuel tank.
Afterwards,energize the glow-plug and try to
restart the engine, to burn off any fuel that may
remain inside the engine. Repeat this
procedure until the engine fails to fire. Do this
while the engine is still warm.
4. Then, inject some after-run oil into the
engine, and rotate the engine with an
electric starter for 4 to 5 seconds to
distribute the oil to all the working parts.
Note:
Do not inject after-run oil into the
carburetor as this may cause the O-rings
inside the carburetor to deteriorate. These
procedures will reduce the risks of starting
difficulties or corrosion after a period of
storage.