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FUEL SYSTEM/CARBURETION
4.7
outside this temperature and/or altitude range. The
jetting installed in production is not intended for all
altitudes and/or temperatures. In addition, air screw
/ pilot screw adjustments and PVT adjustments may
be required to suit operating conditions.
CARBURETOR JETTING
CAUTION:
A main jet that is too small will cause a lean
operating condition resulting in serious engine
damage. Select the correct main jet carefully for
elevation and temperature according to the ATV
specifications charts in Chapter 1 or in the
Owner’s Safety and Maintenance Manual for each
particular model.
IMPORTANT: The following guidelines must be
followed when establishing a main jet setting:
1. Select the lowest anticipated temperature at
which the machine will be operated.
2. Determine the lowest approximate altitude at
which the machine will be operated.
3. Select the correct main jet from the chart in
Chapter 1.
4. Clutching changes may also be required for
changes in elevation. Refer to clutching chart in
Chapter 1 for recommendations.
MIKUNI JET PART NUMBERS
Main Jets
Jet Number Part Number
112.5 3130554
115 3130555
117.5 3130556
120 3130557
122.5 3130558
125 3130559
127.5 3130560
130 3130561
132.5 3130562
135 3130563
137.5 3130564
140 3130527
142.5 3130566
145 3130567
147.5 3130568
150 3130569
152.5 3130570
155 3130571
157.5 3130572
160 3131141
162.5 3131142
165 3131143
167.5 3131144
170 3131145
Jet Number
Part Number
40.0 3130624
42.5 3130526
Pilot Jets
CV CARBURETOR SYSTEM
FUNCTION
Carburetor Component Function
System Main
Components
Main
Function
Main
Affect
Float
System
(Level Control)
Inlet Pipe,
Needle and
Seat, Float,
Float Pin
Maintains
specified
fuel level in
float cham-
ber (carbu-
retor float
bowl)
All systems
All throttle
ranges
Venting Passages in
Carburetor,
Vent lines
to frame
Supplies
atmospheric
pressure to
float cham-
ber
All systems
All throttle
ranges
Starter
(Choke/En-
richment)
Choke Lever,
Cable, Plung-
er, Return
Spring, Carb
Passages
(Starter Jet,
Starter Bleed
Pipe)
Supplies
additional
fuel air mix-
ture neces-
sary for cold
starting
All throttle
ranges
Greatest ef-
fect at low
throttle set-
tings and
idle
Pilot (Idle
System)
Pilot Jet/
Passage-
ways, Pilot-
Mixture
Screw with
Spring
Washer and
Sealing O-
Ring, By-
pass Ports
(Behind
Throttle
Plate), Pilot
Air Jet, Pilot
Outlet,
Throttle
Plate
Primarily
supplies fuel
at idle and
low throttle
positions
Mainly idle
to 1/4
throttle
Minimal ef-
fect after 1/2
throttle
Main Sys-
tem
Main Jet,
Main Air Jet,
Main Air
Passage,
Needle Jet,
Jet Needle,
Vacuum
Slide,
Throttle
Plate
Supplies
fuel at mid-
range and
high throttle
settings.
1/4tofull
throttle