WM, Workshop Manual, K650, K700, K950, K1250, 2001-06, Power ...

Fuel system
3
Carburettor design
Carburettor design
D
C
The carburettor can be divided into three
different functional units: the metering
section, mixing section, and pumping
section.
The carburettor can be divided into three
different functional units: the metering
section, mixing section, and pumping
section.
Metering section
The nozzles and control function for the
fuel are placed here.
Metering section
The nozzles and control function for the
fuel are placed here.
The needle valve (C) and metering diaphragm
(D) are vital parts for the functioning
of the carburettor.
The mixing section
The fuel and air are mixed here.
The mixing section
The fuel and air are mixed to the correct
proportions in this part of the carburettor.
The choke (E) and throttle valves (F) are
placed here.
The main jet nozzle is located in the
middle of the venturi (the narrowest point
on the inlet).
F
E
Pumping section
This pumps fuel from the tank to the
carburettor.
Pumping section
The pump diaphragm (G) which pumps
fuel from the tank to the carburettor’s
metering unit is located here.
The membrane is activated by pressure
variations in the engine crankcase via an
impulse channel (H).
If the channel is blocked, e.g. by grease
or an incorrectly turned gasket, the pump
will not function and the engine will not
start.
H
G
A A
Jets
EPA-models have fixed carburettor jets, which means that the fuel/air mixture can not
be adjusted manually.
The right-hand carburettor in the illustration has fixed jets (A).
The nozzles can be cleaned and possibly changed once the sealing plugs have been
removed.
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