Yamaha XT660R S Service Manual

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ENG
CYLINDER HEAD
EAS00229
CHECKING THE CYLINDER HEAD
1. Eliminate:
• combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
_
Do not use a sharp instrument to avoid damag-
ing or scratching:
• spark plug bore threads
• valve seats
2. Check:
• cylinder head
Damage/scratches
→
Replace.
• cylinder head water jacket
Mineral deposits/rust
→
Eliminate.
3. Measure:
• cylinder head warpage
Out of specification
→
Resurface the cylin-
der head.
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a. Place a straightedge
1
and a thickness
gauge
2
across the cylinder head.
b. Measure the warpage.
c. If the limit is exceeded, resurface the cylin-
der head as follows.
d. Place 400 ~ 600 grit wet sandpaper on the
surface plate and resurface the cylinder
head using a figure-eight sanding pattern.
NOTE:
_
To ensure an even surface, rotate the cylinder
head several times.
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Maximum cylinder head warpage
0.03 mm (0.0012 in)
1
2

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