1. Fout-carburetor
   Four-piston
2. Four-cycle

The four-stroke engine is otherwise known as the four-cycle engine. It's an internal combustion engine in which the piston completes four seperate strokes.

1. Output
   Intake
2. Compression

Intake is the first stroke of a four-stroke engine. This is also known as induction or suction. It begins with the piston in the top dead center and ends at the bottom dead center.

1. Compression
   Multiplication
2. Exclusion

The second stroke of a four-stroke engine is compression. It begins just at the end of the intake stroke and ends top dead center. This is when the piston compresses the air-fuel mixture.

1. Conflation
   Expulsion
2. Combustion

This is where the combustion engine gets its name. The third stroke is combustion, otherwise known as power or ignition.

1. Propelling​
   Exhaust
2. Cooling

The last stroke of the four-stroke engine is exhaust. This is also known as outlet. In the exhaust stroke, the piston turns from bottom dead center back to top dead center.

1. Henry Ford
   Nikolaus August Otto
2. Hans Zimmerman

In 1864, Otto and Eugen Langen founded the first internal combustion engine production company. It was titled NA Otto and Company.

1. Pablo Raybeck
   Gottlieb Daimler
2. Fritz Stevens

Gottlieb Daimler is a popular name in motorcycle engine mechanics. He and Wilhelm Maybach helped to create the first internal combustion engine that compressed the fuel mixture​ prior to combustion, leading to better efficiency. By the time Daimler joined, NA Otto and Company was renamed Deutz Gas Engine Manufacturing Company.

1. Daimler Reitwagen
   Ottomobile
2. Maybach Teich

The Daimler Reitwagen was the first car to use the Otto combustion engine. It used a hot-tube ignition system and fuel known as Ligroin.

1. Electric ignition
   Carburetor​
2. Both

Otto's company, Deutz, is credited with creating the first carburetor and electric ignition system. The company was located in Germany, a hotbed for auto innovation.

1. Vibration
   Spark
2. Light

As the air/fuel mixture is being compressed, it's an electric spark which ignites this mixture. This occurs close to top dead center at a low rpm.

1. Rises
   Stays the same
2. Slows

As engine rpm rises, the speed of the flame from stays the same. This allows the spark point to advance earlier in the cycle, allowing the charge to combust before the power stroke begins.

1. 10%
   20%
2. 30%

A compressed-charge engine has an operation efficiency of 30%. An atmospheric or non-compression engine operates at 12% efficiency.

1. Pre-ignition
   Over-cooling
2. Slow speeds

Due to the heat caused by compressed charge engines, it can lead to pre-ignition. When this occurs at the wrong time, it can damage the engine.

1. Coolant
   Water
2. Chemical composition​ of fuel

The chemical composition of the fuel is what keeps the compressed fuel mixture from igniting too early. There are several grades of fuel that are designed​ to accomodate different types of engines.

1. Consumption
   Evaporation
2. Self-ignition

The octane rating of a given fuel measures the fuel's resistance to pre-ignition. A higher numerical octane rating allows for a higher compression ratio.

1. Yes
2. No

Owners of diesel engines do not have to worry about pre-ignition. But they do have to worry about whether or not combustion can be started.

1. Propane
   Cetane
2. Heptane

The Cetane rating refers to how likely it is that a diesel fuel is going to ignite. Diesel fuels have low volatility, and that's why it's hard to start diesel engines when they're cold.

1. Air
   Water
2. Fuel

The maximum power of a four-stroke engine is determined by the amount of air it can take in. However, the amount of power generated by a piston engine is determined by its size.

1. Intake
   Exhaust
2. Both

To improve an engine's power, it's best to remove irregularities to both the intake and exhaust paths. Such flaws include casting flaws.

1. Heat released through coolant
   Over-acceleration
2. Under-combustion

Internal combustion engines only use 30% or so of the supplied energy. The rest of it is wasted - some in the form of heat released through coolant.

1. Deplete
2. Improve

If you recovered even a small fraction of the heat lost from the motor, you'd significantly improve the engine's performance. As little as 6% would increase engine efficiency.

1. Air
   Water
2. Liquid

When you supercharge your engine, you're pushing more air in the cylinder so that more power can be produced. A supercharger can be powered by the engine crankshaft.

1. Power input
2. Power output

Supercharging increases the power output limits of an internal combustion engine. This is relative to the displacement of the engine.

1. Similar
2. Dissimilar​

Supercharging and turbocharging are similar. The difference is that a turbocharger is driven by the engine's exhaust gases, by means of a turbine.

1. Affordable
   Efficient
2. Durable

Turbocharging makes your engine more efficient because it's using exhaust pressure that would otherwise be wasted. The only design limitation is the turbo lag.

1. Something unmentionable
   Four-strokes of the engine
2. Motorcycle maintenance

"Suck, squeeze, bang, blow" is a funny way of remembering the four strokes of the engine. The strokes are intake, compression, combustion and exhaust.

1. 4
   2
2. 1

The four strokes of the engine require two revolutions of the crankshaft. Each stroke refers to one full stroke of the piston.

1. Upward
2. Downward

During intake, the piston moves downward, drawing in vaporized fuel and air. This is done while the exhaust valve is held shut by a spring.

1. Closes
2. Opens

During the second stroke, the poppet valve is forced shut by higher cylinder pressure. The momentum then drives the piston upward, compressing the air and fuel that were taken in during the first stroke.

1. Cam light
   Spark plug
2. Gaslight

It's during the third stroke that the spark plug fires, igniting the compressed fuel. When the fuel burns and expands, it drives the piston downward.

1. Solitary
   Cam/lifter
2. Cylinder​

The exhaust valve is opened by the cam/lifter mechanism. Following this, the upward stroke of the piston drives the exhaust fuel out of the cylinder.

1. Exhaust pipe
   Cylinder
2. Clutch

Larger four-stroke engines often contain more than one cylinder. They also have various arrangements for the camshaft.

1. Four-stroke engines
2. Two-stroke engines

Four-stroke engines last longer than two-stroke engines. They also use gas more efficiently.

1. 2x
   75%
2. 50%

Four-stroke engines are just about half as powerful as two-stroke engines. Another disadvantage is that they fire once every two revolutions.

1. 1
   2
2. Depends on the cylinders

The number of pistons in your four-stroke engine is directly related to the number of cylinders. There's one piston per cylinder.