2002 YAMAHA YZ85 seat adjustment

CHAPTER 3
REGULAR INSPECTION AND
ADJUSTMENTS
MAINTENANCE INTERVALS................... 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE................................ 3-4
ENGINE...................................................... 3-5
CHASSIS................................................. 3-16
ELECTRICAL........................................... 3-35
CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS.................................. 4-1
EXHAUST PIPE AND SILENCER............. 4-2
RADIATOR................................................ 4-3
CARBURETOR AND REED VALVE......... 4-6
CYLINDER HEAD, CYLINDER
AND PISTON........................................... 4-15
CLUTCH AND PRIMARY
DRIVEN GEAR........................................ 4-26
KICK SHAFT, SHIFT SHAFT
AND PRIMARY DRIVE GEAR................. 4-33
WATER PUMP......................................... 4-41
CDI MAGNETO........................................ 4-45
ENGINE REMOVAL................................. 4-49
CRANKCASE AND CRANKSHAFT........ 4-53
TRANSMISSION, SHIFT CAM
AND SHIFT FORK................................... 4-59

3 - 14
INSP
ADJ
PILOT AIR SCREW ADJUSTMENT
1. Adjust:
lPilot air screw 1
Adjustment steps:
NOTE:
To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot air screw has
been individually set at the factry. Before
adjusting the pilot air screw, turn it in fully and
count the number of turns. Record this num-
ber as the factry-set number of turns out.
lTurn in the pilot air screw until it is lightly
seated.
lTurn out the pilot air screw by the speci-
fied number of turns.
Pilot air screw:
2 turns out (example)
5PA30230
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it up.
2. Adjust:
lEngine idling speed
Adjustment steps:
lTurn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
To increase idle speed ® Turn the throt-
tle stop screw 1 in a.
To decrease idle speed ® Turn the throt-
tle stop screw 1 out b.
5PA30240
EXHAUST PIPE INSPECTION
1. Inspect:
lO-ring 1
Damage ® Replace.
NOTE:
Install the O-rings with their depressed a fac-
ing inward.
5PA30250
PILOT AIR SCREW ADJUSTMENT/ENGINE IDLING
SPEED ADJUSTMENT/EXHAUST PIPE INSPECTION

4 - 10
ENGCARBURETOR AND REED VALVE
Float height
1. Measure:
lFloat height a
Out of specification ® Adjust.
Float height:
18 ~ 20 mm (0.71 ~ 0.79 in)
Measurement and adjustment steps:
lHold the carburetor in an upside down
position.
lMeasure the distance between the mating
surface of the float chamber and top of the
float using a vernier calipers.
NOTE:
The float arm should be resting on the nee-
dle valve, but not compressing the needle
valve.
lIf the float height is not within specification,
inspect the valve seat and needle valve.
lIf either is worn, replace them both.
lIf both are fine, adjust the float height by
bending the float tab b on the float.
lRecheck the float height.
5PA40180
5PA40190
EC464600
Float
1. Inspect:
lFloat 1
Damage ® Replace.
5PA40200
EC464701
Reed valve
1. Measure:
lReed valve bending a
Out of limit ® Replace.
Reed valve bending limit:
0.2 mm (0.008 in)
5PA40210

7 - 15
TUNSETTING
EC72C001
Choosing set length
1. Place a stand or block under the engine to
put the rear wheel above the floor, and
measure the length a between the rear
wheel axle center and the rear fender hold-
ing bolt.
5PA70160
2. Remove the stand or block from the engine
and with a rider astride the seat, measure
the sunken length b between the rear
wheel axle center and the rear fender hold-
ing bolt.
5PA70170
3. Loosen the locknut 1 and make adjust-
ment by turning the spring adjuster 2 to
achieve the standard figure from the sub-
traction of the length b from the length a.
Standard figure:
75 ~ 85 mm (3.0 ~ 3.3 in)
5PA70180
NOTE:
lIf the machine is new and after it is broken in,
the same set length of the spring may
change because of the initial fatigue, etc. of
the spring. Therefore, be sure to make re-
evaluation.
lIf the standard figure cannot be achieved by
adjusting the spring adjuster and changing
the spring set length, replace the spring with
an optional one and make re-adjustment.

7 - 18
TUNSETTING
Suspension setting
lFront fork
NOTE:
lIf any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
lBefore any change, set the rear shock absorber sunken length to the standard figure 75 ~ 85 mm
(3.0 ~ 3.3 in).
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff over entire range
{{{Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range{{{{Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement{Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out{{Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end{Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out{Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement{{{{Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture{{Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 80 ~ 85 mm (3.1 ~ 3.3 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture{{Compression damping
Balance with rear end
Spring
Oil level (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 75 ~ 80 mm (3.0 ~ 3.1 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).

7 - 19
TUNSETTING
lRear shock absorber
NOTE:
lIf any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
lAdjust the damping in 2-click increments or decrements.
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff, tending to sink
{{Rebound damping
Spring set lengthTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 75 ~ 80 mm (3.0 ~ 3.1 in)
when one passenger is astride seat.
Spongy and unstable{{Rebound damping
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Replace with stiff spring.
Heavy and dragging{{Rebound damping
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Replace with soft spring.
Poor road gripping{Rebound damping
Compression damping
Spring set length
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Turn adjuster clockwise (about 2 clicks) to increase
damping.
Set sunken length for 75 ~ 80 mm (3.0 ~ 3.1 in)
when one passenger is astride seat.
Replace with soft spring.
Bottoming out{{Compression damping
Spring set length
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Set sunken length for 75 ~ 80 mm (3.0 ~ 3.1 in)
when one passenger in astride seat.
Replace with stiff spring.
Bouncing{{Rebound damping
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Replace with soft spring.
Stiff travel{{Compression damping
Spring set length
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 80 ~ 85 mm (3.1 ~ 3.3 in)
when one passenger is astride seat.
Replace with soft spring.