Yamaha MX250 - Page 105

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SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
Valve seat contact width
(Exhaust)
0.7–0.9 mm (0.0276–0.0354 in)
Limit (Intake) 1.4 mm (0.055 in)
Limit (Exhaust) 1.4 mm (0.055 in)
Valve margin thickness
(Intake)
1.0–1.4 mm (0.039–0.055 in)
Valve margin thickness
(Exhaust)
1.0–1.4 mm (0.039–0.055 in)
Valve stem runout limit 0.01 mm (0.0004 in)
Valve guide:
Guide inside diameter (Intake) 6.000–6.012 mm (0.2362–0.2367 in)
Guide inside diameter (Exhaust) 6.000–6.012 mm (0.2362–0.2367 in)
Stem to guide clearance (Intake) 0.037–0.064 mm (0.0015–0.0025 in)
Stem to guide clearance
(Exhaust)
0.045–0.072 mm (0.0018–0.0028 in)
Valve clearance (cold)
Intake 0.05–0.09 mm (0.0020–0.0035 in)
Exhaust 0.05–0.09 mm (0.0020–0.0035 in)
Push rod:
Runout limit 0.15 mm (0.0059 in)
Valve spring:
Valve spring free length (Intake) 36.2 mm (1.4252 in)
Valve spring free length
(Exhaust)
36.2 mm (1.4252 in)
Limit (Intake) 34.39 mm (1.3539 in)
Limit (Exhaust) 34.39 mm (1.3539 in)
Installed length (Intake) 29.0 mm (1.1417 in)
Installed length (Exhaust) 29.0 mm (1.1417 in)
Installed compression spring
force (Intake)
91.20–104.93 N (9.12–10.49 kgf, 20.50–23.59 lbf)
Installed compression spring
force (Exhaust)
91.20–104.93 N (9.12–10.49 kgf, 20.50–23.59 lbf)
Tilt limit 1.7 mm (0.0669 in)
Carburetor:
Type/manufacture RUXING
Bore size ø22 (MX250)
ø24 (MX300)
Main jet 1.03 mm (0.040 in) (MX250)
1.14 mm (0.044 in) (MX300)
Main air jet 1.55 mm (0.061 in)
1.8 mm (0.070 in)
Pilot air jet 1.0 mm (0.039 in)