The Small Engine Quiz


By: Robin Tyler

7 Min Quiz

Image: jamievanbuskirk/E+/Getty Images

About This Quiz

In the wonderful world of automotive engineering, you will come across all manner of engine sizes, from the gas-guzzling V8s with huge displacement to hybrid engines, which use a combination of electric and fossil fuel power.

Often, however, the role of the small engine is downplayed. These engines are certainly just as important in the auto industry as well in other realms outside automobiles. Small engines have not only powered some of the most iconic cars ever designed -- and there are a few that immediately spring to mind -- they also are the go-to powerplant for many other pieces of machinery.

Perhaps the most obvious, of course, is the lawnmower. Before electric lawnmowers came around, just about every lawnmower in the world was powered by a two-stroke gasoline engine. And we have all tried to start those! Sometimes you get a bigger workout starting the mower than cutting the lawn! Small gasoline engines are also found in chain saws.

But that's not all. What about motorcycles, scooters and minibikes? Many of these are also powered by small two-stroke engines. These engines are also the power source for outboard motors that you might find on a small fishing boat. But just how much do you know about these hard-working engines? This quiz is going to put your small engine knowledge to the ultimate test! Good luck!

From the options below, pick the number of cylinders that correspond to the number found in a small gasoline engine.

When you think of small engines, the first thing that should pop into your mind is a two-stroke engine and probably one that you would find on a motorcycle. Modern small engines are not only two-stroke, however. Many auto manufacturers have introduced three-cylinder engines over the last few decades.


Which of these vehicles is most likely to have what would be considered a small engine?

Two-stroke engines are almost as old as the automobile itself. And yes, the most likely place to find one would be in a motorcycle. But not large motorcycles, more those ones that sound like souped up sewing machines! That said, two-stroke engines deliver a fair amount of grunt and have excellent power-to-weight ratios.


Who invented the first two-stroke engine with in-cylinder compression?

Although two-stroke engines had been seen before Dugald Clerk's design, he was the first to build a two-stroke engine with in-cylinder compression like we know today in modern engines. His design is considered to be the world's first proper two-stroke engine.


In what year did Dugald Clerk design his engine?

A Scottish engineer, Clerk invented his in-cylinder two-stroke engine in 1878. He applied for and was given a patent in 1881 for his design. Clerk's engines were not that small, however, as they needed an additional pumping cylinder.


In a small engine, which part is responsible for combusting the fuel/air mixture?

Much like any other engine, a small gasoline engine works in exactly the same way as its larger counterparts. And that means the fuel/air mixture entering the cylinder needs to be combusted while it is compressed. And to do that, a spark plug is needed.


True or false? A two-stroke engine found on a motorcycle is water-cooled.

The two-stroke engines that are found on scooters and small motorcycles are not water-cooled. Why should they be? With the engine exposed, a motorcycle two-stroke engine is a perfect powerplant to be air-cooled.


Which other ways are air-cooled engines cooled?

Some motorcycles engines have special fins on the cylinder barrel and the cylinder head. This clever design means the engine is kept cool with the minimum of fuss, as air can penetrate deep within it to keep it running at the right temperature.


Small gas engines also power many other machines in our lives. Which of these do you think is powered by a small engine?

An almost perfect example of a small gasoline engine would be the one found in your fuel-driven lawn mower. This two-stroke engines have one job only, to turn the blade that cuts the grass. Simple, yet effective, these engines can be a little noisy!


How do you ensure that the small engine powering your lawnmower stays in tip-top condition?

Although it isn't a car engine and certainly not as sophisticated, the engine in your lawn mower will still need regular checks to ensure you keep it running for years. This means checking the oil level, replacing the spark plug from time to time and checking the plug gap often as well as keeping the engine clean from grass after you have mowed the lawn.


From the options below, what is the main function of a small engine?

Just like any other engine, a small engine like a two-stroke has one job. And that is to turn the energy produced by combusting the air/fuel mixture into mechanical energy. Although there are many parts that are needed to do this, it all starts with the crankshaft.


Which of these auto engines would be considered a small engine?

In 2012, Ford released a three-cylinder engine, the 1.0-liter EcoBoost. Co-developed by German company, FEV Engineering as well as Japanese automaker, Mazda, the 1.0-liter is turbocharged and can produce 123 brake horsepower!


Small engines such as the Ford 1.0-liter EcoBoost will include an air filter. What does it do?

The cleanest air possible is needed in the engine where it is mixed with gasoline and combusted. To achieve this, it is first passed through the air filter where any potentially harmful particles and debris (think small pieces of leaves, for example) are removed.


True or false? Air filters never need to be cleaned or replaced.

Air filters must be cleaned and replaced whenever needed. Just think about it, any kind of filter will get clogged up with the dirt it is filtering. An air filter is no different. Removed large pieces of debris every so often and replace the filter when need be. This is normally done during a car service.


Battery terminals on engines tend to get a little dirty, and small engines are no different. How should you clean them?

Baking soda is a brilliant general purpose cleaner! To clean dirty battery terminals, use a wire brush and some baking soda. This will ensure that they make proper contact with the battery at all times.


Name the car part that draws air that is filtered into the crankcase.

A breather is the part of your car engine that draws air into the crankcase. It is filled with various filtering systems to help keep oil mist and other vapors from entering the air filter. Usually a pipe, it also releases trapped gases in the compartment of the engine.


Lubricants used in engines are often rated according to their viscosity. What does that mean?

When talking about viscosity in liquids, it has to do with their thickness and consistency. For example, water is not as viscous as oil. In engines, oil is used to lubricate the moving parts within the engine. Without it, metal would grind on metal. For this reason, oil needs to be very viscous.


Gases that form as a result of the burning of the fuel/air mixture in a small engine are released into the exhaust system through this. What is it called?

An exhaust valve is found in the cylinder head. It is driven by the camshaft and releases exhaust gases after the combustion of the air/fuel mixture. These gases are super hot and the exhaust valve is one of the hottest places in an engine.


A piston is made up of a few parts. Which is NOT part of it, however?

A piston is made up of a few parts including the skirt, head and ring grooves. The cylinder is not part of a piston, however. It is the sheath in which the piston moves and where the combustion of the air/fuel mixture takes place.


In a 500cc engine, what connects the spark plugs to the distributor cap and ignition coil?

The spark plug leads conduct the electrical current from the ignition coil to the spark plugs. This then creates the spark to start combustion within the engine, exploding the air/fuel mixture.


In 1959, one of the most iconic cars of all time, the Mini Mk 1 was released. Was the engine powering the first models considered a small engine?

In 1959, the Mini Mk 1 was introduced to the world. And what a popular car it proved to be! The first Minis had a range of motors with the smallest a mere 848 cc fas engine. This little engine pushed the Mini to a speed of just over 70 mph.


In a small engine, what does a compression ring do?

In any engine, including a small engine, the compression ring is extremely important. It is tasked with providing a tight seal between the piston and the cylinder. This helps the air/fuel mixture to be compressed effectively, as well as ensuring the combustion of the air/fuel mixture is as effective as it should be.


In a small engine, which of these parts will wear over time and need to be replaced?

Some parts in an engine, even a small engine, will wear with usage. Bearings are one such part. Their main bearing is tasked with holding the crankshaft in place and will wear over time. From time to time, therefore, it will need to be replaced.


Small engines such as those that are found in chainsaws or lawn mowers can be easily maintained or repaired by someone with just a little bit of mechanical knowledge. If you do have major problems , however, you should ________?

If you have ever messed around on an engine, a two-stroke gasoline engine that drives a lawn mower should not be too difficult for you to maintain. That said, if you come across a problem that you are unsure of how to fix, consulting a professional or taking it to the manufacturer is your best bet.


In a small engine, what connects the piston to the crankshaft?

The pistons in a small engine connect to the crankshaft, just like they would in a larger engine. The part that connects them is called a connection rod and it joins the piston at two points, usually. If a connecting rod breaks, a mechanic will usually tell you that you have "dropped a rod".


Without this vital engine part, a small engine on a car is not starting. Can you name it?

If your car's engine is turning over sluggishly when starting, or nothing happens except for a ticking sound, it's likely your battery is the problem. That is always the first place to check. Luckily, small engines do not need big batteries to turn them over.


In a small engine, where does compression happen?

A small engine is no different from a V8. When the air/fuel mixture is compressed by a piston, it is done within the cylinder itself. There are just fewer cylinders than you would find in a large engine, that's the only difference.


What is the radiator's purpose in a small engine?

A radiator dissipates the heat that engine coolant carries from the engine into it. It then circulates the now-cooler engine coolant back into the engine to do the same again.


The camshaft in a small engine has protrusions on it. What are these are called?

Each camshaft has lobes on it that serve a very specific purpose. As the camshaft rotates, these lobes open and close valves which let the air/fuel mixture into the engine and let the gases out after combustion.


Many small engines, such as a lawnmower engine, make use of a choke. What does a choke do?

In older two-stroke engines, those with carburetors, you would find a choke. This was used to restrict the air entering the engine, enriching the air/fuel mixture when the engine started. Modern engines that use valves have no need for a choke.


What burns within the engine to keep the combustion process going and the engine running?

The air/gasoline mixture is ignited by the spark from the spark plug, prompting the combustion necessary to keep the engine running. In a two-stroke engine with a carburetor, the amount of air entering the engine is regulated by the choke on startup.


True or false? The intake valve on a small engine is bigger than the exhaust valve.

When you compare the intake valve to the exhaust valve in a small engine, well actually any engine, you will find that the intake valve is bigger than the exhaust valve. Why? Well, the exhaust valve is one of the hottest parts within the engine as it lets out superheated gases.


Name the part that turns a small car engine over during the startup process.

When you turn the key in your ignition, the starter motor engages. It turns the engine over, starting it. A faulty starter motor means the car won't start. Sometimes, a stater motor can jam and a simple tap with a hammer can get it working again.


In a lawnmower engine, how often should the engine oil be changed?

Although it uses far less oil than a small motor car engine, a lawnmower engine still needs oil to help lubricate mechanical parts. This should be changed after every 25 hours of use, as over time, the oil will lose viscosity and not lubricate as efficiently as it once did.


What can the engine block on a small engine also be known as?

An engine block is the part of the engine that houses many of the critical pieces that make a car's powerplant tick over. This includes parts such as the cylinders, valves and pistons, to name a few. An engine block can also be called a cylinder block.


A popular mini car of the 1950s, which of these small engines was found in the BMW Isetta?

Mini cars have a certain charm, and perhaps the most famous of them all is the BMW Isetta. Interestingly, this was not a BMW design but built under license. BMW built the Isetta between 1955 and 1962. It was powered by a 250 cc four-stroke engine.


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