What valves are used in some two-stroke engines to control fuel flow directly into the crankcase?

Reed valves are commonly used in high-performance versions of the two-stroke engine, where they control the fuel-air mixture admitted to the cylinder. As the piston rises in the cylinder a vacuum is created in the crankcase beneath the piston.

How is the air fuel mixture drawn into an engine?

The most common engine is a 4-stroke engine. During the intake stroke, the fuel and air mixture is drawn into the cylinder with the exhaust valve closed. Then the air and fuel mixture is compressed in a compression stroke. At the top of the stroke, the spark plug ignites the mixture.

How does air fuel mixture move from the crankcase to the cylinder?

The air-fuel mixture moves into the engine’s cylinder through the appropriately named intake valve. Once the piston has reached BDC, the intake valve closes. This effectively traps the mixture of air and fuel inside of the cylinder.

Why are 2 stroke engines so loud?

Two-stroke engines do not have intake and exhaust valves to regulate the flow of fresh air into, and exhaust gas out of the combustion chamber. As a result, there are two sound waves leaving the exhaust on every stroke (or combustion cycle) resulting in a higher frequency or pitch, and therefore louder noise.

What is the most common problem with 2 stroke carburetors?

Many 2-cycle engines have problems and are sent to the junk yard before their time. Typical problems include hard starting, rough running, a need to adjust the carburetor during use to keep the engine from stalling, a need to rev the engine to keep it from dying, and not starting at all.

How does a 2 stroke engine lubricate the crankshaft?

In a two-stroke engine, on the other hand, the crankcase is serving as a pressurization chamber to force air/fuel into the cylinder, so it can’t hold a thick oil. Instead, you mix oil in with the gas to lubricate the crankshaft, connecting rod and cylinder walls.

What does supercharger do to a car?

“Supercharger” is the generic term for an air compressor used to increase the pressure or density of air entering an engine, providing more oxygen with which to burn fuel.

How does a 2 stroke engine stay lubricated?

Lubrication. Two-stroke engines use their crankcase to pressurize the air-fuel mixture before transfer to the cylinder. Unlike four-stroke engines, they cannot be lubricated by oil contained in the crankcase and sump: lubricating oil would be swept up and burnt with the fuel.

What prevents the air-fuel mixture from leaving with the exhaust?

Pressure
Pressure pulse exhaust tuning is an effective way of increasing power and efficiency in two-cycle engines. Exhaust sound waves reflected back into the manifold create a back pressure that stops the fuel mixture from leaving the cylinder before the piston closes the port.

Why do 2 strokes have big exhaust?

That bulge is called an expansion chamber, and it is used to increase the horsepower of the engine (see this page for a photo). The basic idea behind an expansion chamber is to use the momentum and pressure of the exhaust gases to create a pump that squeezes more air and fuel into the cylinder during the intake stroke.

https://www.youtube.com/watch?v=Jc07PsjtUUQ