- 31 -
7-1-2 SLOW SYSTEM
The pilot system feeds the fuel to the engine during idling and low-speed operation.
The fuel is fed through the main jet (M.J) to the slow jet (S.J), where it is metered, and mixed with the air
metered by the slow air bleed (S.A.B).
The fuel-air mixture is fed to the engine through the idle port (I.P) and slow port(S.P).
During engine idling, the fuel is mainly fed from the idle port (I.P).
7-1-3 MAIN SYSTEM
The main system feeds the fuel to the engine during medium and high-speed operation.
The fuel is metered by the main jet (M.J) and fed to the main nozzle (M.N). The air metered by the main
air bleed (M.A.B) is mixed with the fuel through the bleed holes in the main nozzle (M.N), and the mixture
is atomized out of the main bore. It is mixed again with the air taken through the air cleaner into an
optimum fuel-air mixture, which is supplied to the engine.
7-1-4 CHOKE
The choke (C) is used for easy start in the cold season. When the recoil starter is pulled with a closed
choke (C), the negative pressure applied to the main nozzle increases and draws much fuel accordingly;
thus easily start up the engine.
7-2 DISASSEMBLY AND REASSEMBLY (See Fig.7-2)
Apart from mechanical failures, most of carburetor troubles are caused by an incorrect mixing ratio,
which may arise mainly due to a clogged up air or fuel passage in jets, or fuel level variations. In order to
assure proper flow of air and fuel, the carburetor must be kept clean at all times. The carburetor disas-
sembly and reassembly procedures are as follows.
7-2-1 THROTTLE SYSTEM
(1) Remove the Philips screw (-2) and throttle
valve (-1), and pull out the throttle shaft (-11).
When reassemble the throttle valve, apply a
screw-lock agent to philips screw and tighten
it with a tightening torque of 0.39~1.47 N
・
m
(4~15 kg
・
cm) (0.3~1.1ft
・
lb).
(2) The spring (-41) can be taken out by removing
the throttle stop screw (-40).
*Exercise care not to damage throttle valve edge.
7-2-2 CHOKE SYSTEM
(1) Remove the clip (-4) and choke valve (-3), and
pull out the choke shaft (-8).
(2) When mounting the choke valve, mark sure
that the cutout of the choke valve locates on
the right side when viewed from the outside.
Fig. 7-2
-14
-17
-12
-16
-19
-18
-15
-22
-5
-40
-41
-32
-11
-2
-1
-4
-3
-8
-61
Содержание EY15-3
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