Yamaha XT660R S 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 XT660R S Specifications

General

Displacement	660 cc
Bore x Stroke	100.0 mm x 84.0 mm
Compression Ratio	10.0:1
Fuel System	Fuel Injection
Ignition System	TCI
Starter System	Electric
Transmission System	5-speed
Final Drive	Chain
Front Suspension System	Telescopic forks
Front Tyre	90/90-21 M/C 54S
Rear Tyre	130/80-17 M/C 65S
Overall Width	865 mm
Overall Height	1, 230 mm
Seat Height	865 mm
Wheelbase	1, 505 mm
Wet Weight	181 kg
Fuel Tank Capacity	15 litres
Oil Tank Capacity	2.9 litres
Engine Type	Liquid-cooled, 4-stroke, single cylinder, SOHC
Maximum Power	48hp (35kW) @ 6, 000rpm
Frame	Steel diamond
Rear Suspension System	Swingarm, (link suspension)
Front Brake	Single 298mm disc, 2-piston caliper
Rear Brake	Single Disc, 245 mm