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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.
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.
Click the arrow to continue
INCORRECT
Think back, there are 3 components of the mixture.
Click the arrow to return to the question
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.
Click the arrow to advance
INCORRECT
If a chainsaw has a 2-stroke engine, think back and try to remember if there is another one that may have it.
Click the arrow to return to the question
INCORRECT
A car isn’t light enough to have a 2-stroke engine, think about what the 2-stroke engines can handle.
Click the arrow to return to the question
INCORRECT
If a Dirt Bike has a two-stroke engine, wouldn’t something smaller have one too?
Click the arrow to return to the question
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
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.
Click the arrow to advance to the next question
INCORRECT
Think back, the 4 stroke is heavier than the 2 stroke and the 4 stroke is meant for bigger equipment.
Click the arrow to return to the question
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
Click the arrow to advance
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.
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.
QUESTION 3
What is one ADVANTAGE of a 2-stroke engine?
A. LighterB. More DurableC. More Fuel Efficient
CORRECT
The 2-stroke is lighter than the 4-stroke engine.
Click the arrow to advance to the next question
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.
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.
Click the arrow to return to the question
CORRECT
All of these options have 2 stroke engines on them.
Click the arrow to advance to the next question
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