Yamaha 25 NMHOS [43/245] Power unit e30hmh 30hmh 30hwh models

69R3J11

2-18

Maintenance specification

Power unit (E30HMH, 30HMH, 30HWH models)

Item Unit

Model

E30HMH 30HMH 30HWH

Power unit

Minimum compression kPa 570 (5.7, 83)

pressure (*1) (kgf/cm

, psi)

Cylinder head

Warpage limit mm (in) 0.1 (0.0039)

(lines indicate straightedge

position)

Cylinder

Bore size mm (in) 72.000–72.020 (2.8346–2.8354)

Piston

Piston diameter (D) mm (in) 71.935–71.960 (2.8321–2.8331)

Measuring point (H) mm (in) 10.0 (0.39)

Piston clearance mm (in) 0.060–0.065 (0.0024–0.0026)

(reference data)

Piston pin boss bore mm (in) 19.904–19.915 (0.7836–0.7841)

Oversize piston

1st mm (in) 0.25 (0.010)

2nd mm (in) 0.50 (0.020)

Oversize piston diameter

1st mm (in) 72.185–72.210 (2.8419–2.8429)

2nd mm (in) 72.435–72.460 (2.8518–2.8528)

Piston pin

Outside diameter mm (in) 19.895–19.900 (0.7833–0.7835)

(*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.

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