Yamaha MT-03 - Service manual > Front fork

Removing the front fork legs

The following procedure applies to both of the front fork legs.

1. Stand the motorcycle on a level surface.

WARNING

Securely support the motorcycle so that there is no danger of it falling over.

Place the motorcycle on a suitable stand so that the front wheel is elevated.

2. Loosen:

• Upper bracket pinch bolt "1"
• Cap bolt "2"
• Under bracket pinch bolt "3"

WARNING

Before loosening the upper and under bracket pinch bolts, support the front fork leg.

3. Remove:

• Front fork leg

Disassembling the front fork legs

The following procedure applies to both of the front fork legs.

1. Remove:

• Cap bolt
• Washer
• Spacer
• Fork spring

2. Drain:

• Fork oil

NOTE:

Stroke the inner tube several times while draining the fork oil.

3. Remove:

• Dust seal "1"
•  Oil seal clip "2" (with a flat-head screwdriver)

CAUTION:

Do not scratch the inner tube.

4. Remove:

• Damper rod assembly bolt

NOTE:

While holding the damper rod assembly with the damper rod holder "1" and T-handle "2", loosen the damper rod assembly bolt.

Damper rod holder 90890-01460 T-handle 90890-01326

5. Remove:

• Inner tube

a. Hold the front fork leg horizontally.

b. Securely clamp the brake caliper bracket in a vise with soft jaws.

c. Separate the inner tube from the outer tube by pulling the inner tube forcefully but carefully.

CAUTION:

• Excessive force will damage the oil seal and bushing. A damaged oil seal or bushing must be replaced.
• Avoid bottoming the inner tube into the outer tube during the above procedure, as the oil flow stopper will be damaged.

Checking the front fork legs

The following procedure applies to both of the front fork legs.

1. Check:

• Inner tube "1"
•  Outer tube "2"

Bends/ damage/ scratches → Replace.

WARNING

Do not attempt to straighten a bent inner tube as this may dangerously weaken it.

2. Measure:

• Spring free length "a" Out of specification → Replace.

Spring free length 376.0 mm (14.80 in) <Limit> : 368.0 mm (14.48 in)

3. Check:

• Damper rod "1" Damage/ wear Replace.

  Obstruction → Blow out all of the oil passages with compressed air.

• Oil flow stopper "2" Damage → Replace.

CAUTION:

• The front fork leg has a built-in damper adjusting rod and a very sophisticated internal construction, which are particularly sensitive to foreign material.
• When disassembling and assembling the front fork leg, do not allow any foreign material to enter the front fork.

4. Check:

• Cap bolt O-ring.

  Damage/wear → Replace.

Assembling the front fork legs

The following procedure applies to both of the front fork legs.

WARNING

• Make sure the oil levels in both front fork legs are equal.
• Uneven oil levels can result in poor handling and a loss of stability.

NOTE:

When assembling the front fork leg, be sure to replace the following parts:

• inner tube bushing
• outer tube bushing
• oil seal
• dust seal
• before assembling the front fork leg, make sure all of the components are clean.

1. Install:

• Inner tube busing
• Outer tube busing
• Oil flow stopper
• Damper rod "1"
• Rebound spring "2"
• Copper washer

WARNING

Always use new copper washer.

CAUTION:

Allow the damper rod assembly to slide slowly down the inner tube "3" until it protrudes from the bottom of the inner tube.

Be careful not to damage the inner tube.

2. Lubricate:

• Inner tube's outer surface

Recommended lubricant Fork oil 10W or equivalent

3. Tighten:

• Damper rod assembly bolt "1"

Damper rod assembly bolt 30 Nm (3.0 m*kg, 22 ft*lb) LOCTITE

NOTE:

While holding the damper rod assembly with the damper rod holder "2" and T-handle "3", tighten the damper rod assembly bolt.

Damper rod holder 90890-01460 T-handle 90890-01326

4. Install:

• Outer tube bushing "1" (with the fork seal driver weight "3" and fork seal driver attachment "4"
• Washer "2"

Fork seal driver weight 90890-01367 Fork seal driver attachment 90890-01374

5. Install:

• Oil seal "1" (with the fork seal driver weight and fork seal driver attachment)

CAUTION:

Make sure the numbered side of the oil seal faces up.

NOTE:

• Before installing the oil seal, lubricate its lips with lithium-soap-based grease.
• Lubricate the outer surface of the inner tube with fork oil.
• Before installing the oil seal, cover the top of the front fork leg with a plastic bag "2" to protect the oil seal during installation.

6. Install:

• Oil seal clip "1"

NOTE:

Adjust the oil seal clip so that it fits into the outer tube's groove.

7. Install:

• Dust seal "1" (with the fork seal driver weight)

Fork seal driver weight 90890-01367

8. Fill:

• Front fork leg (with the specified amount of the recommended fork oil)

Quantity (each front fork leg) 570.0 cm3 (19.27 US oz) (20.06 Imp.oz) Recommended oil Fork oil 10W or equivalent

CAUTION:

• Be sure to use the recommended fork oil.

  Other oils may have an adverse effect on front fork performance.

• When disassembling and assembling the front fork leg, do not allow any foreign material to enter the front fork.

9. Measure:

• Front fork leg oil level "a" Out of specification → Correct.

Front fork leg oil level (from the top of the inner tube, with the inner tube fully compressed and without the fork spring) 95.0 mm (3.74 in)

NOTE:

• While filling the front fork leg, keep it upright.
• After filling, slowly pump the front fork leg up and down to distribute the fork oil.

10. Install:

• Spring "1"
• Spring seat "2"
• O-ring
• Cap bolt

NOTE:

• Install the spring with the smaller pitch "a" facing up.
• Before installing the cap bolt, lubricate its O-ring with lithium-soap-based grease.
• Temporarily tighten the cap bolt.

b. Larger pitch

Installing the front fork legs

The following procedure applies to both of the front fork legs.

1. Install:

• Front fork leg

Temporarily tighten the upper and under bracket pinch bolts.

NOTE:

Make sure the inner fork tube is flush with the top of the upper bracket.

2. Tighten:

• Under bracket pinch bolt "3"

Under bracket pinch bolt 28 Nm (2.8 m*kg, 20 ft*lb)

• Cap bolt "2"

Cap bolt 18 Nm (1.8 m*kg, 13 ft*lb)

• Upper bracket pinch bolt "1"

Upper bracket pinch bolt 28 Nm (2.8 m*kg, 20 ft*lb)

WARNING

Make sure the brake hoses are routed properly.

See also: