SUBSEQUENT READJUSTMENTS
Once the engine has been run-in and the carburetor
controls properly set up, it should be unnecessary to
alter the mixture settings, except to make minor
adjustments to the Needle Valve occasionally, to take
account of variations in climatic condisitions.
The use of a different fuel, however, particularly one
containing more, or less, nitromethane and / or a
different type or proportion of lubricating oil, is likely to
call for some readjustment of the Needle-Valve.
Remember that, as a safety measure, it is advisable
to increase the Needle Valve opening by an extra
half-turn counter-clockwise, prior to establishing a
new setting. The same applies if the silencer type is
changed. A different silencer may alter the exhaust
pressure applied to the fuel feed and call for a revised
Needle-Valve setting.
The use of a different glowplug, or changes to the
mainrotor and its pitch angles may also require
compensating carburettor readjustments.
CARBURETOR CLEANLINESS
The correct functioning of the carburetor depends on
its small fuel orifices remaining clear. The minute
particles of foreign matter that are present in any fuel
can easily partially obstruct these orifices and upset
mixture strength so that engine performance
becomes erratic and unreliable. It is recommended
that fuel is passed through a filter when the tank is
filled and that a good in-line filter is installed between
the fuel tank and carburettor and, furthermore, that
this filter is frequently cleaned to remove dirt and lint
that accumulates on the filter screen. Finally,
occasionally remove the needle-valve holder from the
carburetor as shown in Sketch and extract any
remaining foreign matter that may have lodged in the
location shown in Sketch.
Remove this with
an 8mm spanner
Dirt and fbrous matter
mostly accumulate here
18
