Specifications

Engine Assembly

Theory of operation

The P25 series of engines are piston ported engines.

As the piston travels upward:

• The exhaust port is covered.

• The fuel/air mixture above the piston is com-

pressed. See Figure 8.1.

• Fuel/air mix is drawn into the crankcase.

• The spark plug will fire just before the piston

reaches top dead center, igniting the fuel/air mix-

ture.

As the piston travels downward:

• The exhaust post is uncovered, allowing the burn

gases to escape.

• The piston compresses the fuel/air mix in the

crankcase, forcing the mixture up through trans-

fer ports in the side of the cylinder.

• The fuel/air mixture enters the combustion camber,

flowing towards the intake side of the cylinder.

NOTE: This flow pattern helps to push the exhaust gases

out of the cylinder.

Figure 8.1

Exhaust port

Intake port

Figure 8.2

Exhaust

CHAPTER 8: ENGINE ASSEMBLY

For Parts Call 606-678-9623 or 606-561-4983