Yamaha XF50W Service Manual page 26

Valve springs
Free length
Intake
Exhaust
Installed length(valve closed)
Intake
Exhaust
Compressed spring force(installed)
Intake
Exhaust
Spring tilt
V///////////A
Intake
Exhaust
Winding direction(top view)
Intake
Exhaust
Valve seat reformed
Cylinder
Cylinder arrangement
Bore×stroke
Compression ratio
Bore
Maximum taper
Maximum out-of-round
ENGINE SPECIFICATIONS
Item
— » •
Standard
39.35mm(1.5492in)
41.57mm(1.6366in)
28.0mm(1.1024in)
30.0mm(1.1811in)
91.1~104.9N
(9.3~10.7kg, 20.48~23.58lb)
107.9~124.1N
(11.0~12.7kg, 24.26~27.90lb)
...
...
Clockwise
Clockwise
Yes
Forward inclined single cylinder ...
38.0×43.5mm(1.496×1.713in)
12:1
38.000~38.010mm
(1.496~1.497in)
...
...
2-7
SPEC 0 *
Limit
37.38mm
(1.4717in)
39.49mm
(1.5547in)
...
...
...
...
2.5°/1.7mm
(2.5°/0.0669in)
2.5°/1.8mm
(2.5°/0.0709in)
...
...
...
...
...
...
0.05mm
(0.0020in)
0.05mm
(0.0020in)