Yamaha 2011 YZ250, Owner'S Manual

Page: 74 / 174

4-10
CARBURETOR AND REED VALVE
CHECKING THE FLOAT
1. Inspect:
• Float "1"
Damage
→
Replace.
CHECKING THE REED VALVE
1. Measure:
• Reed valve bending "a"
Out of specification
→
Replace.
2. Measure:
• Valve stopper height "a"
Out of specification
→
Adjust stop-
per/Replace valve stopper.
INSTALLING THE REED VALVE
1. Install:
• Reed valve "1"
• Stopper (reed valve) "2"
• Screw (reed valve) "3"
• Install the reed valve with the reed
valve bending as shown.
• Note the cut "a" in the lower corner
of the reed and stopper plate.
Tighten each screw gradually to
avoid warping.
2. Install:
• Gasket (reed valve) "1"
• Plate (reed valve) "2"
• Reed valve assembly "3"
• Reed valve spacer "4"
Install the reed valve spacer with its
chamfered side "a" to the right.
3. Install:
• Carburetor joint "1"
• Bolt (carburetor joint) "2"
ASSEMBLING THE CARBURETOR
1. Install:
• Power jet "1"
To carburetor "2".
2. Install:
• O-ring "1"
• Solenoid valve "2"
To carburetor.
• Before installing the solenoid
valve, blow air on the solenoid
valve and its installing location
on the carburetor in order to re-
move any foreign particles such
as chips etc.
• Apply the engine oil on the sole-
noid valve thread.
3. Install:
• Pilot air screw "1"
• Throttle stop screw "2"
Note the following installation
points:
a. Turn in the pilot air screw until it is
lightly seated.
b. Turn out the pilot air screw by the
number of turns recorded before
removing.
Reed valve bending limit
"a":
0.2 mm (0.01 in)
Valve stopper height "a":
10.3–10.7 mm (0.41–
0.42 in)
Screw (reed valve):
1 Nm (0.1 m•kg, 0.7
ft•lb)
Bolt (carburetor joint):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Pilot air screw:
1-1/4 turns out
* 2-1/4 turns out
(for reference only)
* Except for USA and CDN