89
CHAPTER 5 The Two-Stroke Cycle Engine
Copyright Goodheart-Willcox Co., Inc.
of the crankcase. Known as a half-crankshaft,
the crankshaft has only one end. The counter-
balance is designed to balance the crankshaft
as the crankshaft rotates. One end of the crank-
pin is pressed into the counterbalance, leaving
the other end open. The needle bearing on the
crankpin is serviceable.
Piston
The basic parts of the piston are the:
• Piston.
• Ring(s).
• Alignment pin.
• Piston pin.
• Piston pin retainer.
Cylinder
Crankshaft
Connecting rod
Crankpin
Crankcase cover
A B
C
Cylinder
Cylinder and upper
crankcase half
Crankshaft
Crankcase halves Crankcase cover
Goodheart-Willcox Publisher
Figure 5-11. Crankcase designs. A—In this engine, the two crankcase halves are bolted together and
the cylinder is bolted on top. B—In this engine design, the cylinder and upper crankcase half are cast
together. C—In this engine, half of a crankshaft is inserted through the crankcase shell. A cover is
bolted to the backside of the crankcase. The cylinder is bolted on top.