How many rotations/degrees are in one firing cycle?
1 rotation/360°.
Which actions happen during the up stroke?
Intake & compression.
Which actions happen during the down stroke?
Power & exhaust.
Which part of a 2-stroke engine mimics the functions of 4-stroke valves?
Ports.
How is cross-scavenging achieved?
By adding a lip to the piston face.
How is loop scavenging achieved?
By altering the transfer port shape and size.
What is the 2 main functions of the transfer ports?
- To transfer the air/fuel mixture from crankcase to combustion chamber.
- To assist with exhaust scavenging.
List 4 intake port control designs.
- Piston port.
- Reed valve.
- Combination piston port & reed valve.
- Rotary disc valve.
What is a piston port?
Cut outs in the skirt of a piston on one or more sides.
How does a piston port affect fuel intake?
Allows non-restricted intake.
How does a reed valve operate under pressure change?
Opens under low pressure, closes under high pressure.
Where is the intake valve located in a rotary disc valve setup?
On crankcase side.
How does a rotary disc operate, and what effect does it have?
It rotates with the crankshaft to open and close ports, producing more effective scavenging.
What system is used to control port size opening and timing?
Power valve systems.
How do power valve system affect engine performance?
They widen the RPM range of usable power/powerband.
