Yamaha YZF-R25, Service Manual

Page: 36 / 456

ENGINE SPECIFICATIONS
2-3
Thermostat
Valve opening temperature 80.5–83.5 °C (176.90–182.30 °F)
Valve full open temperature 95.0 °C (203.00 °F)
Valve lift (full open) 3.0 mm (0.12 in)
Radiator core
Width 145.8 mm (5.74 in)
Height 270.0 mm (10.63 in)
Depth 24.0 mm (0.94 in)
Water pump
Water pump type Single suction centrifugal pump
Reduction ratio 41/23 (1.783)
Spark plug(s)
Manufacturer/model NGK/CR9E
Spark plug gap 0.7–0.8 mm (0.028–0.031 in)
Cylinder head
Combustion chamber volume 9.00–9.80 cm³ (0.55–0.60 cu.in)
Warpage limit 0.05 mm (0.0020 in)
Camshaft
Drive system Chain drive (right)
Camshaft cap inside diameter 22.500–22.521 mm (0.8858–0.8867 in)
Camshaft journal diameter 22.459–22.472 mm (0.8842–0.8847 in)
Camshaft-journal-to-camshaft-cap clearance 0.028–0.062 mm (0.0011–0.0024 in)
Camshaft lobe dimensions
Lobe height (Intake) 32.050–32.150 mm (1.2618–1.2657 in)
Limit 31.950 mm (1.2579 in)
Base circle diameter (Intake) 24.972–25.072 mm (0.9831–0.9871 in)
Limit 24.872 mm (0.9792 in)
Lobe height (Exhaust) 31.650–31.750 mm (1.2461–1.2500 in)
Limit 31.550 mm (1.2421 in)
Base circle diameter (Exhaust) 25.082–25.182 mm (0.9875–0.9914 in)
Limit 24.982 mm (0.9835 in)
Camshaft runout limit 0.030 mm (0.0012 in)
Timing chain
Tensioning system Automatic
Valve, valve seat, valve guide
Valve clearance (cold)
Intake 0.11–0.18 mm (0.0043–0.0071 in)
Exhaust 0.21–0.30 mm (0.0083–0.0118 in)
Valve dimensions
Valve head diameter (intake) 22.90–23.10 mm (0.9016–0.9094 in)
Valve head diameter (exhaust) 19.40–19.60 mm (0.7638–0.7717 in)
Valve seat contact width (intake) 0.90–1.20 mm (0.0354–0.0472 in)
Valve seat contact width (exhaust) 0.90–1.20 mm (0.0354–0.0472 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)