Hit-and-miss engine

The main usage here was to drive traditional skiff style utility and fishing boats.

When these engines were designed, technology was less advanced, and manufacturers made all parts very large.

The mixer creates the correct fuel-air mixture by means of a needle valve attached to a weighted or spring-loaded piston, usually in conjunction with an oil-damped dashpot.

Fuel is simply fed to the mixer, where due to the effect of Bernoulli's principle, it is self-metered in the Venturi created below the weighted piston by the action of the attached needle valve, the method used to this day[when?]

A buzz coil uses battery power to generate a series of high voltage pulses that are fed to the spark plug.

This makes for a messy environment, as oil and sometimes grease are thrown from the engine and run onto the ground.

Another disadvantage is that dirt and dust can get on all moving engine parts, causing excessive wear and malfunctions.

When an engine runs under load for a period of time, it is common for the water in the reservoir to boil.

However, they incorporate some innovative designs in several areas, often in an attempt to circumvent patent infringement for a particular component.

The actuator mechanism to govern speed is also varied depending on patents existing and the governor used.

When the hit-and-miss engine is operating above its set speed, the governor holds the exhaust valve open, preventing a vacuum in the cylinder and causing the intake valve to remain closed, thus interrupting the Otto cycle firing mechanism.

When the engine is operating at or below its set speed, the governor lets the exhaust valve close.

On the next down-stroke, a vacuum in the cylinder opens the intake valve and lets the fuel-air mixture enter.

They powered pumps for cultivation, saws for cutting wood, generators for electricity in rural areas, farm equipment, and many other stationary applications.

Flywheel engines are extremely heavy for the power produced, and run at very slow speeds.

Older engines required a lot of maintenance and were not easily incorporated into mobile applications.

Their next step was the model LA, which was a totally enclosed engine (except for the valve system) featuring self-lubrication (oil in the crankcase), reliable spark plug ignition, faster-speed operation (up to about 750-800 RPM), and light in weight compared to earlier generations.

Companies like Briggs and Stratton were also producing lightweight air-cooled engines in the 0.5–2 hp (0.37–1.5 kW) range and used much lighter-weight materials.

Maintenance is less of a problem with modern flywheel engines than older ones due to their enclosed crankcases and more advanced materials.

Thousands of out-of-use flywheel engines were scrapped in the iron and steel drives of World War II, but many survived and have been restored to working order by enthusiasts.