Overheating; Poor Braking Performance; Faulty Front Fork Legs; Unstable Handling - Yamaha Star XVS950A 2009 Service Manual

EAS28600

OVERHEATING

Engine
1. Cylinder head(s) and piston(s)
• Heavy carbon buildup
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity
• Inferior oil quality
Fuel system
1. Throttle body(-ies)
• Damaged or loose throttle body joint
2. Air filter
• Clogged air filter element
Chassis
1. Brake(s)
• Dragging brake
Electrical system
1. Spark plug(s)
• Incorrect spark plug gap
• Incorrect spark plug heat range
2. Ignition system
• Faulty ECU
EAS28620

POOR BRAKING PERFORMANCE

• Worn brake pad
• Worn brake disc
• Air in hydraulic brake system
• Leaking brake fluid
• Faulty brake caliper kit
• Faulty brake caliper seal
• Loose union bolt
• Damaged brake hose
• Oil or grease on the brake disc
• Oil or grease on the brake pad
• Incorrect brake fluid level
EAS28650

FAULTY FRONT FORK LEGS

Leaking oil
• Bent, damaged or rusty inner tube
• Cracked or damaged outer tube
• Improperly installed oil seal
• Damaged oil seal lip
• Incorrect oil level (high)
• Loose damper rod assembly bolt
• Damaged damper rod assembly bolt copper
washer
• Cracked or damaged cap bolt O-ring
TROUBLESHOOTING
Malfunction
• Bent or damaged inner tube
• Bent or damaged outer tube
• Damaged fork spring
• Worn or damaged outer tube bushing
• Bent or damaged damper rod
• Incorrect oil viscosity
• Incorrect oil level
EAS28670

UNSTABLE HANDLING

1. Handlebar
• Bent or improperly installed handlebar
2. Steering head components
• Improperly installed upper bracket
• Improperly installed lower bracket
(improperly tightened ring nut)
• Bent steering stem
• Damaged ball bearing or bearing race
3. Front fork leg(s)
• Uneven oil levels (both front fork legs)
• Unevenly tensioned fork spring (both
front fork legs)
• Broken fork spring
• Bent or damaged inner tube
• Bent or damaged outer tube
4. Swingarm
• Worn bearing or bushing
• Bent or damaged swingarm
5. Rear shock absorber assembly
• Faulty rear shock absorber spring
• Leaking oil or gas
6. Tire(s)
• Uneven tire pressures (front and rear)
• Incorrect tire pressure
• Uneven tire wear
7. Wheel(s)
• Incorrect wheel balance
• Deformed cast wheel
• Damaged wheel bearing
• Bent or loose wheel axle
• Excessive wheel runout
8. Frame
• Bent frame
• Damaged steering head pipe
• Improperly installed bearing race
EAS28710
FAULTY LIGHTING OR SIGNALING SYS-
TEM
Headlight does not come on
• Wrong headlight bulb
• Too many electrical accessories
• Hard charging
8-3