Yamaha YFM25RY Automobile User Manual


 
ENGINE SPECIFICATIONS
2-5
Valve, valve seat, valve guide
Valve clearance (cold)
Intake 0.05–0.10 mm (0.0020–0.0039 in)
Exhaust 0.10–0.15 mm (0.0039–0.0059 in)
Valve dimensions
Valve head diameter A (intake) 33.90–34.10 mm (1.3346–1.3425 in)
Valve head diameter A (exhaust) 28.40–28.60 mm (1.1181–1.1260 in)
Valve face width B (intake) 2.26 mm (0.0890 in)
Valve face width B (exhaust) 2.26 mm (0.0890 in)
Valve seat width C (intake) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.60 mm (0.06 in)
Valve seat width C (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.60 mm (0.06 in)
Valve margin thickness D (intake) 0.80–1.20 mm (0.0315–0.0472 in)
Valve margin thickness D (exhaust) 0.80–1.20 mm (0.0315–0.0472 in)
Valve stem diameter (intake) 5.975–5.990 mm (0.2352–0.2358 in)
Limit 5.945 mm (0.234 in)
Valve stem diameter (exhaust) 5.960–5.975 mm (0.2346–0.2352 in)
Limit 5.930 mm (0.233 in)
Valve guide inside diameter (intake) 6.000–6.012 mm (0.2362–0.2367 in)
Limit 6.050 mm (0.238 in)
Valve guide inside diameter (exhaust) 6.000–6.012 mm (0.2362–0.2367 in)
Limit 6.050 mm (0.238 in)
Valve-stem-to-valve-guide clearance (intake) 0.010–0.037 mm (0.0004–0.0015 in)
Limit 0.080 mm (0.003 in)
Valve-stem-to-valve-guide clearance
(exhaust) 0.025–0.052 mm (0.0010–0.0020 in)
Limit 0.100 mm (0.004 in)
Valve stem runout limit 0.01 mm (0.0004 in)
Cylinder head valve seat width (intake) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.60 mm (0.06 in)
Cylinder head valve seat width (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.60 mm (0.06 in)