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CHAPTER 4
ENGINE
CARBURETOR ..........................................4-1
CYLINDER HEAD ......................................4-8
CAMSHAFT AND ROCKER ARMS ........4-13
VALVES AND VALVE SPRINGS ............4-16
CYLINDER AND PISTON ........................4-21
CLUTCH ...................................................4-27
KICK AXLE ..............................................4-33
SHIFT SHAFT ..........................................4-34
OIL PUMP ................................................4-36
CDI MAGNETO (TT-R90) ........................4-39
CDI MAGNETO AND
STARTER CLUTCH (TT-R90E) ...............4-41
CRANKCASE AND CRANKSHAFT ........4-45
SHIFT FORK, SHIFT CAM AND
TRANSMISSION ......................................4-48
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL .......5-1
FRONT FORK ..........................................5-10
HANDLEBAR ...........................................5-13
STEERING ...............................................5-18
SWINGARM .............................................5-20
CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS AND
WIRING DIAGRAM ....................................6-1
IGNITION SYSTEM ....................................6-3
ELECTRIC STARTING SYSTEM
(TT-R90E) ..................................................6-7
CHARGING SYSTEM (TT-R90E) ............6-15
CARBURETOR HEATING SYSTEM .......6-17
MAINTENANCE RECORD ......................6-21
Page 37 of 390
GEN
INFO
1 - 7
SPECIAL TOOLS
YM-1312-A, 90890-01312 Fuel level gauge
This gauge is used to measure the fuel level in the
float chamber.YM-1312-A 90890-01312
YM-1326, 90890-01326 T-handle
This tool is used for holding the damper rod holder
when removing or installing the damper rod holder.YM-1326 90890-01326
90890-01186 Fork seal driver attachment
This tool is used to installing the oil seal.90890-01186
YM-8035, 90890-01311 Valve adjusting tool
This tool is necessary for adjusting valve clearance.YM-8035 90890-01311
YM-33963, 90890-01184 Fork seal driver weight
This tool is used to installing the oil seal.YM-33963 90890-01184
YM-34487
90890-06754Dynamic spark tester
Ignition checker
This instrument is necessary for checking the ignition
system components.YM-34487 90890-06754
YM-33975, 90890-01403 Ring nut wrench
This tool is used when tighten the steering ring nut to
specification.YM-33975 90890-01403
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.YM-91042 90890-04086
YS-1880-A, 90890-01701 Sheave holder
This tool is used for when loosening or tightening the
flywheel magneto securing nut.YS-1880-A 90890-01701
Part number Tool name/How to use Illustration
Page 70 of 390
SPEC
2 - 11 CHASSIS
Item Standard Limit
Steering system:
Steering bearing type Angular bearing ----
Front suspension:
Front fork travel 110 mm (4.33 in) ----
Fork spring free length 425.1 mm (16.74 in) 417 mm (16.4 in)
Fork spring fitting length 415.1 mm (16.34 in) ----
Spring rate, STD K = 3.4 N/mm
(0.35 kg/mm, 19.41 lb/in)----
Optional spring/spacer No ----
Oil capacity 64 cm
3
(2.26 Imp oz, 2.16 US oz) ----
Oil level 185 mm (7.28 in) ----
Oil grade Fork oil 15W or equivalent ----
Rear suspension:
Shock absorber travel 48 mm (1.89 in) ----
Spring free length 169 mm (6.65 in) ----
Fitting length 165 mm (6.5 in) ----
Spring rate, STD K = 45.6 N/mm
(4.65 kg/mm, 260 lb/in)----
Optional spring No ----
Enclosed gas pressure 2,000 kPa
(20 kg/cm
2, 290 psi)----
Swingarm:
Swingarm free play limit
End ---- 1.0 mm (0.04 in)
Side clearance ---- 0.3 mm (0.01 in)
Wheel:
Front wheel type Spoke wheel ----
Rear wheel type Spoke wheel ----
Front rim size/material 14 × 1.40/steel ----
Rear rim size/material 12 × 1.60/steel ----
Rim runout limit:
Radial ---- 2.0 mm (0.08 in)
Lateral ---- 2.0 mm (0.08 in)
Drive chain:
Type/manufacturer DID420(I)/DAIDO ----
Number of links 86 links ----
Chain slack 40 ~ 53 mm (1.6 ~ 2.1 in) ----
Chain length (15 links) ---- 194.3 mm
(7.65 in)
MAINTENANCE SPECIFICATIONS
Page 72 of 390
SPEC
2 - 13
NOTE:
1. First, tighten the ring nut approximately 38 Nm (3.8 m kg, 27 ft lb) by using the ring nut
wrench and turn the steering right and left a few times; then loosen the ring nut one turn.
2. Retighten the ring nut 1 Nm (0.1 m kg, 0.7 ft lb).
-marked portion shall be checked for torque tightening after break-in or before each ride.Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Engine mounting:
Engine and frame (front-upper) M8 × 1.25 1 30 3.0 22
Engine and frame (rear-upper) M8 × 1.25 1 26 2.6 19
Engine and frame (rear-lower) M10 × 1.25 1 48 4.8 35
Starter cable and frame M11 × 1.25 1 1 0.1 0.7
Pivot shaft and nut M10 × 1.25 1 30 3.0 22
Handle crown and steering shaft M10 × 1.25 1 40 4.0 29
Front fork cap bolt M20 × 1.0 2 40 4.0 29
Under bracket and front fork M10 × 1.25 2 33 3.3 24
Damper rod bolt M8 × 1.25 2 20 2.0 14
Handle crown and handlebar holder (lower) M10 × 1.25 2 40 4.0 29
Handlebar holder (upper)(TT-R90) M6 × 1.0 4 13 1.3 9.4
(TT-R90E) M8 × 1.25 4 23 2.3 17
Front brake cable holder and front fork M6 × 1.0 2 7 0.7 5.1
Steering ring nut M25 1 Refer to NOTE.
Fuel tank and fuel cock M6 × 1.0 2 7 0.7 5.1
Fuel tank and frame M6 × 1.0 2 7 0.7 5.1
Grab bar and frame M6 × 1.0 4 13 1.3 9.4
Brake lever mounting (bolt) M6 × 1.0 1 3 0.3 2.2
Brake lever mounting (nut) M6 × 1.0 1 4 0.4 2.9
Front brake camshaft lever and camshaft M6 × 1.0 1 7 0.7 5.1
Rear brake camshaft lever and camshaft M6 × 1.0 1 7 0.7 5.1
Front wheel axle nut M10 × 1.25 1 35 3.5 25
Rear brake shoe plate tension bar M8 × 1.25 2 26 2.6 19
Wheel drive hub and driven sprocket M8 × 1.25 4 25 2.5 18
Rear wheel axle nut M12 × 1.25 1 60 6.0 43
Wheel nipple (spoke)—64 2 0.2 1.4
Drive chain guard M5 × 0.8 2 4 0.4 2.9
Drive chain support M5 × 0.8 3 4 0.4 2.9
Chain puller locknut M6 × 1.0 2 7 0.7 5.1
Footrest and frame M8 × 1.25 2 30 3.0 22
Battery box (TT-R90E) M6 × 1.0 3 5 0.5 3.6
MAINTENANCE SPECIFICATIONS
Page 166 of 390
3 - 18
INSP
ADJWHEEL INSPECTION/
STEERING HEAD INSPECTION AND ADJUSTMENT
EC36T000
WHEEL INSPECTION
1. Inspect:
Wheel runout
Elevate the wheel and turn it.
Abnormal runout → Replace.
2. Inspect:
Bearing free play
Exist play → Replace.
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suit-
able stand under the engine.
2. Check:
Steering shaft
Grasp the bottom of the forks and gently
rock the fork assembly back and forth.
Free play → Adjust steering head.
3. Check:
Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action → Adjust steering ring
nut.
4. Adjust:
TT-R90
Steering ring nut
Steering ring nut adjustment steps:
Remove the front fender 1.
Remove the handlebar and handle crown.
Loosen the ring nut 2 using the ring nut
wrench 3.
