22
TYPE 70R CARBURETTOR
The sequence in which these controls are
adjusted is explained in the succeeding
sections, under Starting, Running-in and Idle
Adjustment.
The Needle Valve
When set to produce maximum power at full
throttle, this establishes the basic fuel/air
mixture strength. The correct mixture is then
maintained by the carburetor's built-in
automatic mixture control system to cover
the engine's requirements at reduced throttle
settings.
The Mixture Control Valve
This meters fuel flow at part-throttle and idle
speeds to ensure reliable operation as the
throttle is opened and closed.
The Mixture Control Valve is factory set for
the approximate best result. First run the
engine as received and readjust the Mixture
Control Valve only if necessary.
Two mixture controls are provided on this
Carburetor.
Needle Valve
Mixture Control Valve
Air Funnel
Throttle Lever
Regulator
Rotor Guide
Screw
MIXTURE CONTROLS
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NEVER disassemble the fuel pump or pressure
regulator. Their original performance may not be
restored after reassembly.
DO NOT allow foreign matter to enter the fuel
system. Dirt inside the pump or regulator, no
matter how small, may obstruct the flow of fuel and
prevent these components from working properly.
ALWAYS use fuel filters. Keep the fuel tank
scrupulously clean and filter all fuel as it enters the
tank (e.g.via an O.S.'Super-Filter' Code
No.72403050) and use a good quality in-line filter
between the tank and pump. Remember to inspect
filter screens at regular intervals and rinse clean as
necessary.
NEVER use gasoline, kerosene, diesel fuel or
other petroleum products for cleaning the pump,
regulator or fuel lines. Silicone-rubber parts will be
ruined by these materials. Use only alcohol
(methanol) or glow fuel for cleansing these items.
CARE OF FUEL PUMP & REGULATOR
DO NOT obstruct the small rectangular hole at the
bottom of the regulator, nor the regulator will not
function correctly.
NEVER insert anything into the inlet or outlet
nipples in an attempt to clear a suspected
obstruction. (See CARE & MAINTENANCE section
at the back of this booklet.)
When new, 2~3 minutes of running time will be
required for the pump and regulator to begin
functioning properly, During this period you may
not be able to get the full throttle mixture rich
enough. In this case, just run the engine at
approx, 3/4 throttle a little longer.
Rectangular hole
