Yamaha XT660R S Service Manual

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ENG
VALVES AND VALVE SPRINGS
6. Measure:
• valve stem runout
Out of specification → Replace the valve.
NOTE:
_
• When installing a new valve, always replace
the valve guide.
• If the valve is removed or replaced, always
replace the valve stem seal.
EAS00240
CHECKING THE VALVE SEATS
The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
• carbon deposits
(from the valve face and valve seat)
2. Check:
• valve seat
Pitting/wear → Replace the cylinder head.
3. Measure:
• valve seat width a
Out of specification → Replace the cylinder
head.
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a. Apply Mechanic’s blueing dye (Dykem) onto
the valve face.
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
d. Measure the valve seat width.
NOTE:
_
Where the valve seat and valve face contacted
one another, the blueing will have been
removed.
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Valve stem runout
0.010 mm (0.0004 in)
Valve seat width
Intake
1.00 ~ 1.20 mm
(0.0394 ~ 0.0472 in)
Exhaust
1.00 ~ 1.20 mm
(0.0394 ~ 0.0472 in)

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