Power Unit - Yamaha 20C Manual De Servicio

SPEC
C31000-0*

POWER UNIT

Item
Power unit
Compression pressure (*1)
(Reference)
Cylinder head
Warpage limit
(lines indicate straightedge
position)
Cylinder
Bore size
Wear limit
Taper limit
Out-of-round limit
Piston
Piston diameter (D)
Measuring point (H)
Piston-to-cylinder clearance
Piston pin boss bore
Piston pin
Outside diameter
Piston rings
Top ring
Dimension B
Dimension T
End gap
Side clearance
2nd ring
Dimension B
Dimension T
End gap
Side clearance
Reed valve
Valve stopper height
Valve vending limit
Connecting rod
Small end inside diameter
Big end inside diameter
(*1) Measuring conditions:
Ambient temperature 20°C (68°F), wide open throttle, with spark plugs removed from all cylinders.
The figures are for reference only.
MAINTENANCE SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
Unit
kPa
(kgf/cm
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
mm (in)
2 , psi)
67.000–67.020 (2.6378–2.6386)
66.955–66.980 (2.6360–2.6370)
0.040–0.045 (0.0016–0.0018)
18.004–18.015 (0.7088–0.7093)
17.995–18.000 (0.7085–0.7087)
1.97–1.99 (0.0776–0.0783)
2.90–3.10 (0.1142–0.1220)
0.30–0.50 (0.0118–0.0197)
0.02–0.06 (0.0008–0.0024)
1.97–1.99 (0.0776–0.0783)
2.90–3.10 (0.1142–0.1220)
0.30–0.50 (0.0118–0.0197)
0.03–0.07 (0.0012–0.0028)
5.00–5.50 (0.20–0.22)
22.004–22.017 (0.8663–0.8668)
29.004–29.017 (1.1419–1.1424)
2-3
Model
20CMH
834 (8.34, 120.9)
0.10 (0.0039)
67.1 (2.64)
0.08 (0.0032)
0.05 (0.0020)
10.0 (0.39)
0.200 (0.0079)
E