Balancer; Piston And Piston Ring - Yamaha F150A Service Manual

GEN
INFO

Balancer

A two-piece balancer is used in the crankcase to reduce the secondary forces of inertia produced by
reciprocating pistons.
The balancer shaft 1 is driven by the gear on the crankshaft.
The balancer shaft 2 is driven by the gear on the balancer shaft 1.
The two counterrotating balancer shafts rotate at twice the speed of the crankshaft and reduce the
forces of inertia of the connecting rods and each balancer shaft.
Therefore, engine vibration is reduced.
1 Balancer shaft 1
2 Balancer shaft 2

Piston and piston ring

A forged piston has been adopted for durability.
Hard chromium plating is applied to the piston rings.
The top and 2nd piston rings differ and are identified by a mark on each ring.
Install the piston rings on the piston with the identification marks facing up.
1 Top ring
2 2nd ring
3 Upper oil ring rail
4 Lower oil ring rail
1-7
General information
4
3 Piston secondary force of inertia
4 Balancer force of inertia
3
1
S63P1080
2
4
S63P1090
63P3F11