Yamaha WR250F(N), Owner'S Service Manual

Page: 78 / 686

SPEC
2 - 5
MAINTENANCE SPECIFICATIONS
Timing chain:
Timing chain type/No. of links 92RH2010-114M/114 ----
Timing chain adjustment method Automatic ----
Valve, valve seat, valve guide:
Valve clearance (cold) IN 0.10 ~ 0.15 mm
(0.0039 ~ 0.0059 in) ----
EX 0.17 ~ 0.22 mm
(0.0067 ~ 0.0087 in) ----
Valve dimensions:
“A” head diameter IN 22.9 ~ 23.1 mm
(0.9016 ~ 0.9094 in) ----
EX 24.4 ~ 24.6 mm
(0.9606 ~ 0.9685 in) ----
“B” face width IN 2.26 mm (0.089 in) ----
EX 2.26 mm (0.089 in) ----
“C” seat width IN 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in) 1.6 mm
(0.0630 in)
EX 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in) 1.6 mm
(0.0630 in)
“D” margin thickness IN 0.8 mm (0.0315 in) ----
EX 0.7 mm (0.0276 in) ----
Stem outside diameter IN 3.975 ~ 3.990 mm
(0.1565 ~ 0.1571 in) 3.945 mm
(0.1553 in)
EX 4.460 ~ 4.475 mm
(0.1756 ~ 0.1762 in) 4.430 mm
(0.1744 in)
Guide inside diameter IN 4.000 ~ 4.012 mm
(0.1575 ~ 0.1580 in) 4.050 mm
(0.1594 in)
EX 4.500 ~ 4.512 mm
(0.1772 ~ 0.1776 in) 4.550 mm
(0.1791 in)
Stem-to-guide clearance IN 0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in) 0.08 mm
(0.003 in)
EX 0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in) 0.10 mm
(0.004 in)
Item Standard Limit
Head Diameter
B
Face Width
C
Seat Width
D
Margin Thickness
A