3-11
ENGINE
3. Adjust:
• Engine idling speed
Adjustment steps:
a. Turn the starter knob/idle screw
"1" until the specified engine idling
speed is obtained.
Using the digital tachometer, mea-
sure the engine speed with the detec-
tor "c" pinched in the high tension
cord "2" of the ignition coil.
ADJUSTING THE VALVE
CLEARANCE
• This section is intended for those
who have basic knowledge and skill
concerning the servicing of Yama-
ha motorcycles (e.g., Yamaha deal-
ers, service engineers, etc.) Those
who have little knowledge and skill
concerning servicing are requested
not to undertake inspection, adjust-
ment, disassembly, or reassembly
only by reference to this manual. It
may lead to servicing trouble and
mechanical damage.
• The valve clearance should be ad-
justed when the engine is cool to
the touch.
1. Remove:
• Seat
Refer to "SEAT AND SIDE COV-
ERS" section in the CHAPTER 4.
• Fuel tank
Refer to "FUEL TANK" section in
the CHAPTER 6.
2. Remove:
• Spark plug
• Cylinder head cover
Refer to "CAMSHAFTS" section
in the CHAPTER 4.
3. Remove:
• Timing mark accessing screw "1"
• Crankshaft end accessing screw
"2"
• O-ring
4. Check:
• Valve clearance
Out of specification
→
Adjust.
Checking steps:
a. Turn the crankshaft counterclock-
wise with a wrench.
b. Align the alignment mark "a" on
the rotor with the alignment mark
"b" on the crankcase cover.
Make sure that the alignment mark
"c" on the exhaust camshaft sprocket
and the alignment mark "d" on the in-
take camshaft sprocket are aligned
with the edge of the cylinder head.
c. Measure the valve clearance "e"
using a feeler gauge "1".
Record the measured reading if the
clearance is incorrect.
Digital tachometer:
YU-39951-B/90890-
06760
To increase the engine idling
speed
→
Turn the starter
(choke) knob/idling screw
counterclockwise "a".
To decrease the engine idling
speed
→
Turn the starter
(choke) knob/idling screw
clockwise "b".
Engine idling speed:
1,900–2,100 r/min
Valve clearance (cold):
Intake valve:
0.10–0.15 mm
(0.0039–0.0059 in)
Exhaust valve:
0.20–0.25 mm
(0.0079–0.0098 in)
Summary of Contents for YZ450F(B) 2012
Page 4: ......
Page 12: ...1 2 LOCATION OF IMPORTANT LABELS EUROPE ...
Page 13: ...1 3 LOCATION OF IMPORTANT LABELS AUS NZ ZA ...
Page 48: ...2 18 CABLE ROUTING DIAGRAM CABLE ROUTING DIAGRAM ...
Page 50: ...2 20 CABLE ROUTING DIAGRAM F F A B D D C C E F F C C D D B A E 100mm ...
Page 52: ...2 22 CABLE ROUTING DIAGRAM B B F G A A C C D D E E B B G F C C D D E E A A ...
Page 69: ...3 13 ENGINE INTAKE EXHAUST ...
Page 87: ...4 6 RADIATOR 11 Pipe 1 O ring 1 1 Order Part name Q ty Remarks ...
Page 117: ...4 36 OIL PUMP 15 Oil pump drive shaft 1 16 Rotor housing 1 Order Part name Q ty Remarks ...
Page 168: ...5 29 STEERING 10 Bearing race 2 Refer to removal section Order Part name Q ty Remarks ...
Page 227: ......
Page 228: ...PRINTED IN JAPAN E PRINTED ON RECYCLED PAPER ...