2016 YAMAHA YZ250F oil

OIL PUMP AND BALANCER GEAR
5-52
EAS1SM9263
OIL PUMP AND BALANCER GEAR
Removing the oil pump
Order Part name Q’ty Remarks
Primary driven gear Refer to “CLUTCH” on page 5-35.
Right crankcase cover Refer to “CLUTCH” on page 5-35.
1 Oil pump assembly 1
2 Oil pump cover 1
3 Outer rotor 1
4 Dowel pin 1
5 Inner rotor 1
6 Oil pump drive shaft 1
7 Rotor housing 1
For installation, reverse the removal proce-
dure.
2.0 Nm (0.20 m•kgf, 1.4 ftIbf)T.R
.
5 Nm (0.5 mkgf, 3.6 ftIbf)T.R
.
LT
E
3
2
1
4
5
7
6

OIL PUMP AND BALANCER GEAR
5-53
Removing the balancer
Order Part name Q’ty Remarks
Primary driven gear Refer to “CLUTCH” on page 5-35.
Right crankcase cover Refer to “CLUTCH” on page 5-35.
Stator Refer to “AC MAGNETO” on page 5-58.
1 Nut (balancer) 1
2 Nut (primary drive gear) 1
3 Nut (balancer shaft driven gear) 1
4 Conical washer 1
5Balancer 1
6 Conical washer 1
7 Primary drive gear 1
8Collar 1
9 Balancer shaft drive gear 1
10 Conical washer 1
11 Balancer weight gear 1
12 Collar 1
13 Balancer weight 2
For installation, reverse the removal proce-
dure.
T
.R.
75 Nm (7.5 mkgf, 54 ftlbf)T.R.
50 Nm (5.0 mkgf, 36 ftIbf)T
.R.
New
612
11
7
8
13
5
13
T.R.
LT
LT
LT

OIL PUMP AND BALANCER GEAR
5-54
EAS1SM9264REMOVING THE BALANCER
1. Loosen:
• Balancer nut “1”
• Primary drive gear nut “2”
• Balancer weight gear nut “3”
TIP
Place an aluminum plate “a” between the teeth
of the balancer drive gear “4” and balancer
weight gear “5”.
EAS1SM9265CHECKING THE PRIMARY DRIVE GEAR,
BALANCER SHAFT DRIVE GEAR, AND
BALANCER WEIGHT GEAR
1. Check:
• Primary drive gear “1”
• Balancer shaft drive gear “2”
• Balancer weight gear “3”
Wear/damage  Replace.
EAS1SM9266CHECKING THE BALANCER
1. Check:
•Balancer
Crack/damage  Replace.
EAS1SM9267CHECKING THE OIL PUMP
1. Check:
• Oil pump drive gear
• Oil pump driven gear
• Oil pump housing
• Oil pump housing cover
Cracks/damage/wear  Replace the defec-
tive part(s).
2. Measure:
• Inner-rotor-to-outer-rotor-tip clearance “a”
• Outer-rotor-to-oil-pump-housing clearance
“b”
• Oil-pump-housing-to-inner-rotor-and-outer-
rotor clearance “c”
Out of specification  Replace the oil pump.
1
4
a5
2
4a
5
3

OIL PUMP AND BALANCER GEAR
5-55
3. Check:
• Oil pump operation
Rough movement  Repeat steps (1) and
(2) or replace the defective part(s).
EAS1SM9268ASSEMBLING THE OIL PUMP
1. Install:
• Oil pump drive shaft “1”
• Inner rotor “2”
• Dowel pin “3”
TIP
• Apply the engine oil on the oil pump drive
shaft and inner rotor.• Fit the dowel pin into the groove in the inner
rotor.
2. Install:
• Outer rotor “1”
TIP
Apply the engine oil on the outer rotor.
3. Install:
• Oil pump cover “1”
• Oil pump cover screw “2”
EAS1SM9269INSTALLING THE OIL PUMP AND BALANC-
ER GEAR
1. Install:
• Oil pump assembly “1”
• Oil pump assembly bolt “2” Inner-rotor-to-outer-rotor-tip
clearance
Less than
0.150 mm (0.0059 in)
Limit
0.20 mm (0.0079 in)
Outer-rotor-to-oil-pump-housing
clearance
0.13–0.18 mm (0.0051–0.0071 in)
Limit
0.24 mm (0.0094 in)
Oil-pump-housing-to-inner-and-
outer-rotor clearance
0.06–0.11 mm (0.0024–0.0043 in)
Limit
0.17 mm (0.0067 in)
1. Inner rotor
2. Outer rotor
3. Oil pump housing
b
a 1
2
3
c
Oil pump cover screw
2.0 Nm (0.20 m·kgf, 1.4 ft·lbf)
Oil pump assembly bolt
5 Nm (0.5 m·kgf, 3.6 ft·lbf)
LOCTITE®
21
3
1
E
T R..
2
1
T R..

OIL PUMP AND BALANCER GEAR
5-56
ECA
NOTICE
After tightening the bolts, make sure that
the oil pump turns smoothly.
2. Install:
• Collar “1”
• Balancer weight gear “2”
TIP
Install the balancer weight gear and balancer
shaft with their lower splines “a” aligning with
each other.
3. Install:
• Balancer drive gear “1”
• Collar “2”
TIP
• Align the punched mark “a” on the balancer
drive gear with the punched mark “b” on the
balancer weight gear.
• Install the balancer drive gear and crankshaft
with the lower splines “c” aligning with each
other.4. Install:
• Conical washer “1”
• Balancer weight gear nut “2”
• Primary drive gear “3”
• Conical washer “4”
• Primary drive gear nut “5”
•Balancer “6”
• Conical washer “7”
• Balancer nut “8”
1
2
LT
21
Balancer weight gear nut
50 Nm (5.0 m·kgf, 36 ft·lbf)
Primary drive gear nut
75 Nm (7.5 m·kgf, 54 ft·lbf)
Balancer nut
38 Nm (3.8 m·kgf, 27 ft·lbf)
a
b
1
1
2
New
T R..
New
T R..
New
T R..

OIL PUMP AND BALANCER GEAR
5-57
TIP
• Apply engine oil to the contact surface and
threaded portion of the primary drive gear nut.
• Place an aluminum plate “a” between the
teeth of the balancer drive gear “9” and bal-
ancer weight gear “10”.
• Install the conical washer with its convex sur-
face “b” outward.
• Align the balancer flat portion “c” with the flat
portion “d”.
• Apply the engine oil to the contact surface and
threaded portion of the balancer nut.
a
210
b
2 91
b53
a41059
3
E
c
d
6
678
8 b

AC MAGNETO
5-58
EAS1SM9270
AC MAGNETO
Removing the AC magneto
Order Part name Q’ty Remarks
Engine oilDrain.
Refer to “CHANGING THE ENGINE OIL” on
page 3-15.
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left) Refer to “GENERAL CHASSIS” on page 4-1.
1 AC magneto coupler 1 Disconnect.
2 Crankshaft position sensor coupler 1 Disconnect.
3 Shift pedal 1
4 Left crankcase cover 1
5 Gaskets 1
6 Dowel pin 2
7Holder 1
8 Stator assembly 1
9 Rotor 1
10 Woodruff key 1
For installation, reverse the removal proce-
dure.
110
2
4 7 5 8 3
96
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
65 Nm (6.5 mkgf, 47 ftIbf)T.R.
New
LT
6
LT
LT
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.

CRANKCASE
5-61
EAS1SM9275
CRANKCASE
Separating the crankcase
Order Part name Q’ty Remarks
Engine Refer to “ENGINE REMOVAL” on page 5-1.
PistonRefer to “CYLINDER AND PISTON” on page
5-30.
BalancerRefer to “OIL PUMP AND BALANCER
GEAR” on page 5-52.
Kick shaft assembly Refer to “KICKSTATER” on page 5-44.
Segment Refer to “SHIFT SHAFT” on page 5-47.
Stator Refer to “AC MAGNETO” on page 5-58.
1 Timing chain guide (exhaust side) 1
2 Timing chain guide stopper plate 1
3 Timing chain 1
4 Bolt [L = 45 mm (1.77 in)] 7
5 Bolt [L = 60 mm (2.36 in)] 2
6 Bolt [L = 75 mm (2.95 in)] 3
7 Right crankcase 1
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R
.
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R
.
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R
.
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R
.
3
1 5
2
6410 56
4
4
446
9117
8
9
LT