What is the difference between 2 and 4 stroke engines?

By: Zane Taylor

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Directions

Click the Forward arrow to move to the next slide and the back arrow to go to the previous slide.

As you move through the assignment, you will learn the advantages and disadvantages of 2 and 4 stroke engines, then you will take a short quiz.

Hello, I run a lawn service

company but my chainsaw and lawn mower

have stopped working. Can you come and see what the problem is?

You work at a small engine maintenance and repair shop. However, in the shop, you follow the instructions in the book and follow the advice of your boss. Today, you are the person who is making the field calls today and you’re not sure what to do in this situation. You need a quick course to learn how to tell the difference between 2 and 4 stroke engines.

MAIN MENU

2-Stroke 4-Stroke

QUIZ

Advantages of the 2 stroke 2 stroke engines do not have poppet valves. The

sides of the piston work to cover the intake and exhaust ports.

Since there are only 2 strokes of the engine, the engine fires on every revolution which continually generates power.

These engines are also lighter and cheaper to make since these engines are made of Aluminum.

These engines, since they have a mixture that is ignited, can work in any orientation because of the way the engine is made.

.

Disadvantages

2 stroke engines require a special oil and a special ratio (4 oz. oil/ 1 gallon of fuel.)

These engines produce a lot of pollution since the design is not the most efficient and a very small amount of unburnt mixture escapes through the exhaust valve.

Other information

These kinds of engines are used in chainsaws, leaf blowers, dirt bikes, mopeds, jet skis, small outboard motors, and RC planes.

The mixture ignited in the chamber is AIR/FUEL/OIL

The 2 strokes that are paired are INTAKE/COMPRESSION and COMBUSTION/EXHAUST.

Practice Quiz- Question 1

1. What kind of mixture is sent to the combustion chamber?

A. Air/FuelB. Air/Fuel/OilC. Fuel/OilD. Air/Oil

Click the correct answer to continue.

CORRECT!!!

The mixture sent into the combustion chamber is Air/Fuel/Oil.

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INCORRECT

Think back, there are 3 components of the mixture.

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Practice Quiz- Question 2

Which of these uses a 2- stroke engine?

A. ChainsawB. CarC. Dirt BikeD. A and C

CORRECT

A car is too heavy to have a 2-stroke engine, however a chainsaw and a dirt bike are both light enough and maneuverable to merit the benefits of the 2-stroke.

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INCORRECT

If a chainsaw has a 2-stroke engine, think back and try to remember if there is another one that may have it.

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INCORRECT

A car isn’t light enough to have a 2-stroke engine, think about what the 2-stroke engines can handle.

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INCORRECT

If a Dirt Bike has a two-stroke engine, wouldn’t something smaller have one too?

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Practice Quiz- Question 3

What is the oil/fuel ratio in a 2-stroke engine?

A. 4 oz./ 1 galB. 4 oz./ 1 literC. 6 oz./ 1 galD. 6 oz./ 1 liter

CORRECT

The correct ratio is 4 oz./ 1 gal

Click the Home button to return to the Main Menu.

INCORRECT

Check back in the information to see what the ratio is. (Hint: Its oz/ gal)

Advantages of the 4-stroke engine

The 4-stroke engine does have better fuel economy than the 2 stroke engine.

The 4-stroke engine generates more torque than the 2-stroke.

Since the 4-stroke engine is heavier, it is more durable than its 2-stroke counterpart.

These engines do have cleaner emissions since they don’t mix the gasoline and oil when they are firing.

Disadvantages

These types of engines are more complicated since there is more timing required for these engines to work.

The 4-stroke is only half as powerful as its 2-stroke counterpart because the 4-stroke fires on every OTHER crankshaft rotation rather than every time.

Other Information

Only engines with a camshaft, valve train, and poppet valves.

Can run with gas, diesel, kerosene, whiskey, vegetable oil, rocket fuel, and gunpowder.

4-stroke engines are commonly found on Lawn Mowers and anything larger than that.

Practice Quiz- Question 1

What are 4-stroke engines commonly found on?

A. Riding Lawn MowerB. ChainsawC. Hedge Trimmer

CORRECT

Correct, the riding lawn mower is too heavy to handle the 2 stroke engine but the 4 stroke is just right.

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INCORRECT

Think back, the 4 stroke is heavier than the 2 stroke and the 4 stroke is meant for bigger equipment.

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Practice Quiz- Question 2

What is one advantage of a 4 stroke engine over a 2 stroke engine?

A. More DurableB. LightweightC. Fires on every rotation

CORRECT

One advantage of the 4-stroke engine is that it is more durable than its 2-stroke counterpart

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INCORRECT

Think back about what the 2 and 4 stroke engines are made of and how they work.

DECISION TIME

If you have not completed both reviews click on the Home button to go back to the Main Menu, otherwise click the arrow to advance to the next part of the lesson.

Quick Review Video

UPDATE

One last thing before you go out to that job. You need to prove your knowledge with this short quiz.

QUESTION 1

What is the mixture ignited in the chamber of a 2-stroke engine?

A. Fuel/OilB. Air/FuelC. Air/Fuel/OilD. Air/Oil

INCORRECT

That is incorrect. Go back to the question and remember, there are 3 components of the mixture.

CORRECT

That is the correct answer. The mixture is Air/Fuel/Oil. Click the arrow below to go to the next question.

QUESTION 2

What is one DISADVANTAGE of a 4-stroke engine?

A. More PollutionB. Requires Special OilC. More Complicated

CORRECT

One disadvantage of the 4-stroke engine is that it is a little more complicated. Click the arrow to advance to the next question.

INCORRECT

Think about how the engine works and what it is made of.

QUESTION 3

What is one ADVANTAGE of a 2-stroke engine?

A. LighterB. More DurableC. More Fuel Efficient

INCORRECT

Think about the advantages of a two stroke engine. Specifically, the weight of it.

CORRECT

The 2-stroke is lighter than the 4-stroke engine.

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QUESTION 4

What are the 4 strokes of the engine, IN ORDER?

A. Intake, Compression, Combustion, Exhaust

B. Intake, Combustion, Exhaust, Compression

C. Exhaust, Combustion, Intake, Compression

D. Combustion, Intake, Compression, Exhaust

INCORRECT

Think about the order of the strokes. When you think about it, they will fall into order in your head.

CORRECT

That is correct. You are now halfway done!

Click to Advance to the next question.

QUESTION 5

What equipment is a 4-stroke engine commonly found upon?

A. ChainsawB. Hedge TrimmerC. Riding Lawn MowerD. Leaf Blowers

INCORRECT

Think about the weights of the engines and how the pieces of equipment are used.

Click to return to the question

CORRECT

The 4 stroke engine is commonly found on riding lawn mowers.

Click to Advance to the next question

QUESTION 6

What are 2 stroke engines typically found on?

A. ChainsawsB. Hedge TrimmersC. Dirt BikesD. All of the Above

INCORRECT

Think about the way this is used, there may be more than one right answer.

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CORRECT

All of these options have 2 stroke engines on them.

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QUESTION 7

What is the fuel/oil ratio in a 2-stroke engine?

A. 4 oz./ 1 gal B. 4 oz./ 1 liter C. 6 oz./ 1 gal D. 6 oz./ 1 liter

INCORRECT

Think about what units we deal with. It is not too large of a ratio.

Click to return to the question

CORRECT

That is the correct answer. You may remember that question from earlier.

Click to advance to the FINAL QUESTION

QUESTION 8

What did the man at the beginning own that he needed your help with?

A. Lawn Mower/ChainsawB. Chainsaw/Hedge TrimmerC. Lawn Mower/Hedge Trimmer

INCORRECT

What would be common in an agriculture community?

Click to return to the question

CORRECT

CONGRATULATIONS, YOU HAVE COMPLETED THE QUIZ

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CONGRATULATIONS

You have completed your refresher course in just enough time to get to the job and do your job correctly!

Click anywhere to complete the lesson