Yamaha YFM250RX 2008 Service Manual page 28

Item
Valve, valve seat, valve guide
Valve clearance (cold)
Valve dimensions
Head Diameter
"A" head diameter
"B" face width
"C" seat width
"D" margin thickness
Stem outside diameter
Guide inside diameter
Stem-to-guide clearance
Valve stem runout
Valve seat width
ENGINE SPECIFICATIONS
IN 0.05 ~ 0.10 mm (0.0020 ~ 0.0039 in)
EX 0.10 ~ 0.15 mm (0.0039 ~ 0.0059 in)
Face Width
IN 33.90 ~ 34.10 mm (1.3346 ~ 1.3425 in)
EX 28.40 ~ 28.60 mm (1.1181 ~ 1.1260 in)
IN 2.26 mm (0.0890 in)
EX 2.26 mm (0.0890 in)
IN 0.90 ~ 1.10 mm (0.0354 ~ 0.0433 in)
EX 0.90 ~ 1.10 mm (0.0354 ~ 0.0433 in)
IN 0.80 ~ 1.20 mm (0.0315 ~ 0.0472 in)
EX 0.80 ~ 1.20 mm (0.0315 ~ 0.0472 in)
IN 5.975 ~ 5.990 mm (0.2352 ~ 0.2358 in)
EX 5.960 ~ 5.975 mm (0.2346 ~ 0.2352 in)
IN 6.000 ~ 6.012 mm (0.2362 ~ 0.2367 in)
EX 6.000 ~ 6.012 mm (0.2362 ~ 0.2367 in)
IN 0.010 ~ 0.037 mm (0.0004 ~ 0.0015 in)
EX 0.025 ~ 0.052 mm (0.0010 ~ 0.0020 in)
• • •
IN 0.90 ~ 1.10 mm (0.0354 ~ 0.0433 in)
EX 0.90 ~ 1.10 mm (0.0354 ~ 0.0433 in)
2-5
SPEC
Standard
Seat Width Margin Thickness
Limit
• • •
• • •
• • •
• • •
• • •
• • •
1.6 mm
(0.06 in)
1.6 mm
(0.06 in)
• • •
• • •
5.945 mm
(0.234 in)
5.930 mm
(0.233 in)
6.050 mm
(0.238 in)
6.050 mm
(0.238 in)
0.080 mm
(0.003 in)
0.100 mm
(0.004 in)
0.01 mm
(0.0004 in)
1.6 mm
(0.06 in)
1.6 mm
(0.06 in)