Yamaha MTN850-A 2017, Service Manual, Page: 40 / 560

ENGINE SPECIFICATIONS
2-3
Radiator cap valve opening pressure 93.3–122.7 kPa (0.93–1.23 kgf/cm², 13.5–17.8
psi)
Water pump
Water pump type Single suction centrifugal pump
Impeller shaft tilt limit 0.15 mm (0.006 in)
Spark plug(s)
Manufacturer/model NGK/CPR9EA9
Spark plug gap 0.8–0.9 mm (0.031–0.035 in)
Cylinder head
Warpage limit 0.10 mm (0.0039 in)
Camshaft
Camshaft cap inside diameter 24.500–24.521 mm (0.9646–0.9654 in)
Camshaft journal diameter 24.459–24.472 mm (0.9630–0.9635 in)
Camshaft-journal-to-camshaft-cap clearance 0.028–0.062 mm (0.0011–0.0024 in)
Limit 0.080 mm (0.0032 in)
Camshaft lobe dimensions
Lobe height (Intake) 36.290–36.390 mm (1.4287–1.4327 in)
Limit 36.190 mm (1.4248 in)
Lobe height (Exhaust) 35.720–35.820 mm (1.4063–1.4102 in)
Limit 35.620 mm (1.4024 in)
Camshaft runout limit 0.030 mm (0.0012 in)
Valve, valve seat, valve guide
Valve clearance (cold)
Intake 0.11–0.20 mm (0.0043–0.0079 in)
Exhaust 0.26–0.30 mm (0.0102–0.0118 in)
Valve dimensions
Valve seat contact width (intake) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.60 mm (0.06 in)
Valve seat contact width (exhaust) 1.10–1.30 mm (0.0433–0.0512 in)
Limit 1.80 mm (0.07 in)
Valve stem diameter (intake) 4.475–4.490 mm (0.1762–0.1768 in)
Limit 4.445 mm (0.1750 in)
Valve stem diameter (exhaust) 4.460–4.475 mm (0.1756–0.1762 in)
Limit 4.430 mm (0.1744 in)
Valve guide inside diameter (intake) 4.500–4.512 mm (0.1772–0.1776 in)
Valve guide inside diameter (exhaust) 4.500–4.512 mm (0.1772–0.1776 in)
Valve-stem-to-valve-guide clearance (in-
take)
0.010–0.037 mm (0.0004–0.0015 in)
Limit 0.080 mm (0.0032 in)
Valve-stem-to-valve-guide clearance (ex-
haust)
0.025–0.052 mm (0.0010–0.0020 in)
Limit 0.100 mm (0.0039 in)
Valve stem runout 0.010 mm (0.0004 in)
Valve spring
Free length (intake) 39.31 mm (1.55 in)
Limit 37.34 mm (1.47 in)
Free length (exhaust) 37.78 mm (1.49 in)
Limit 35.89 mm (1.41 in)
Spring tilt (intake) 1.7 mm (0.07 in)
Spring tilt (exhaust) 1.6 mm (0.06 in)