Yamaha XT660X Service Manual

9 - 3
TRBL
SHTG
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE/
FAULTY GEAR SHIFTING/FAULTY CLUTCH
EAS00848
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE
Refer to “STARTING FAILURES”.
ENGINE
Air filter
• Clogged air filter element
FUEL SYSTEM
Fuel pump
• Faulty fuel pump
EAS00850
FAULTY GEAR SHIFTING
SHIFTING IS DIFFICULT
Refer to “CLUTCH DRAGS”.
SHIFT PEDAL DOES NOT MOVE
Shift shaft
• Improperly adjusted shift rod
• Bent shift shaft.
Shift drum and shift forks
• Foreign object in a shift drum groove
• Seized shift fork
• Bent shift fork guide bar
Transmission
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission
JUMPS OUT OF GEAR
Shift shaft
• Incorrect shift pedal position
• Improperly returned stopper lever
Shift forks
• Worn shift fork
Shift drum
• Incorrect axial play
• Worn shift drum groove
Transmission
• Worn gear dog
EAS00851
FAULTY CLUTCH
CLUTCH SLIPS
Clutch
• Improperly assembled clutch
• Improperly adjusted clutch cable
• Loose or fatigued clutch spring
• Worn friction plate
• Worn clutch plate
Engine oil
• Incorrect oil level
• Incorrect oil viscosity (low)
• Deteriorated oil
CLUTCH DRAGS
Clutch
• Unevenly tensioned clutch springs
• Warped pressure plate
• Bent clutch plate
• Swollen friction plate
• Bent clutch push rod
• Broken clutch boss
• Burnt primary driven gear bushing
• Match marks not aligned
Engine oil
• Incorrect oil level
• Incorrect oil viscosity (high)
• Deteriorated oil

Yamaha XT660X Specifications

General

Displacement	660cc
Bore x Stroke	100.0 mm x 84.0 mm
Compression Ratio	10.0:1
Fuel System	Fuel Injection
Ignition System	TCI
Transmission	5-speed
Final Drive	Chain
Rear Brake	Single disc, Ø 245 mm
Front Tyre	120/70 R17
Rear Tyre	160/60 R17
Maximum Power	48 HP (35.3 kW) @ 6, 000 rpm
Maximum Torque	58.4Nm (43.1lb-ft) @ 5, 250rpm
Front Suspension	Telescopic fork
Rear Suspension	Swingarm, (link suspension)
Fuel Tank Capacity	15 litres
Engine Type	Liquid-cooled, 4-stroke, single cylinder, SOHC, 4-valves