CARBURETTOR
10
26
A
B
Pump unit
Function
The pump diaphragm (A) is driven by
the pressure variations in the crankcase
that are led to the pulse line on the
pump unit cover.
The fuel on the underside of the dia -
phragm is pumped to the valves (B). The
counter pressure of the measurement
chamber diaphragm on the metering side
regulates the amount the valves open and
the quantity of fuel pumped to the fuel
chamber.
Pump unit
Function
The pump diaphragm (A) is
driven by the pressure variations
in the crankcase.
The fuel on the underside of
the diaphragm is pumped to the
valves (B). The counter pressure
of the measurement chamber
diaphragm regulates the amount
the valves open and the quantity
of fuel pumped to the fuel
chamber.
Inspection
Pump diaphragm leakage is checked as
previously described.
The function of the valve flaps cannot
be pressure tested and must be visually
inspected. The valve flaps must be abso-
lutely flat and close tight against the car-
burettor housing in order for the pump
function to work. If the flaps show signs
of buckling, fatigue or cracking, the dia -
phragm must be replaced.
Inspection
Pump diaphragm leakage is
checked as previously described.
The function of the valve
flaps cannot be pressure tested
and must be visually inspected.
The valve flaps must be absolut -
ely flat and close tight against
the carburettor housing.
Fuel strainer
There is a fine-meshed strainer located on
the fuel inlet to the carburet tor. Inspect
this with a magnifying glass. Loose dirt
particles can be blown away from the
needle valve's seating. If there are depo-
sits that are hard to remove or the mesh
is damaged the strainer must be replaced.
The strainer is dismantled using a
needle or awl. Fit the new strainer with a
.3 in./7 mm punch.
Fuel strainer
Inspect the strainer with a magni-
fying glass. Loose dirt particles
can be blown away from the
needle valve's seating. If there
are deposits that are hard to
remove or the mesh is damaged
the strainer must be replaced.
The strainer is dismantled
using a needle or awl. Fit the
new strainer with a .3 in./7 mm
punch.
Channels
Blowing clean the carburettor
In connection with a service on the
carburettor it is appropriate to blow out
any particles from the channels using
compressed air. The measurement cham-
ber diaphragm and the pump diaphragm
as well as the needle valve must be dis-
mantled before starting to blow clean.
Open the choke valve to give free air
passage through the venturi.
The rings indicate where blowing clean
should be done.
