Cylinder/Piston System Description - Honda Motorcycle Service Manual

CYLINDERIPISTON
SYSTEM DESCRIPTION
CYLINDER
Because the cylinders are afficted by combustion heat and pressure, they are made of a one-piece aluminum or steel casting
with considerable strength and cooling abilities. Air-cooled engines are provided with cooling fins and liquid-cooled engines
are provided with a water jacket; both necessary to cool the engine. With a 4-stroke engine, the cylinder wall has cylindrical
shape. With the 2-stroke engine, however, the exhaust or scavenging ports are open and the characteristics of the engine
depend on the shape, location and size of the ports. These ports are the key parts of a 2-strock engine. Because the piston
rings and piston skirts move against the cylinder walls, a material with high wear resistance is required. For the aluminum
cast cylinder, a steel cylinder sleeve is pressed into the part that directly contacts the piston and rings. In some 2-stroke
engines, the cylinder walls are plated with special hard metal (nickel-silicon carbide coating which is much lighter than the
sleeve type), and which has considerable cooling ability, seizure and wear resistance.
With the sleeve type, the cylinder wall is honed for a finish. Fine grooves are made in the surface to collect and spread the
oil on the cylinder wall to lubricate the piston. With the plated type, neither modification of the cylinder wall nor reboring
is possible. If the cylinder wall is flawed the cylinder must be replaced.
EXAMPLE OF 2-STROKE WlTH SLEEVE TYPE
A
SCAVENGING PORT
EXAMPLE OF2-STROKE ENGINE PROCESSED WlTH NICKEL-SILICON CARBIDE lNikasilo
)
SPECIAL COATING LAYER
Date of Issue: March. 1995
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