Principle Of Operation - RedMax GZ25N Workshop Manual

1. OUTLINE OF STRATO-CHARGED ENGINE

1-2 Principle of Operation

Major difference of the Strato-charged Engine to the conventional 2-stroke engine is that as illustrated on the following drawing, there are lead air intake tubes which are connected to the scavenging port via reed valves.
Due to crankcase depression during the piston upstroke
(intake stroke) to the top dead centre, air-fuel mixture is charged
to the crankcase and lead air is charged to the scavenging
ports though the reed valves.
Scavenging Port
Crankcase
Reed Valve Assy
Lead Air Intake Tube
Air
Air-Fuel Mixture
Carburetor
Air-Fuel Mixture
As piston proceeds to downstroke after the top dead center,
a scavenging port starts to open and lead air in the scavenging
port moves into the cylinder earlier than the air-fuel mixture.
Air
Reed Valve
Air-Fuel Mixture
Lead Air
Scavenging Port
As piston proceeds to upstroke after the bottom dead center,
burnt gas in the cylinder is pushed out through the exhaust
port by lead air. Therefore, direct exhaust of air-fuel mixture
is almost non.
Burnt Gas
Air-Fuel Mixture
Exhaust Port
Lead Air
Air-Fuel Mixture
STRATO CHARGED ENGINE GZ25N
Lead Air
Burnt Gas
Exhaust Port
3