4-stroke engine VS 2-stroke engine: How are they different?

Have you ever wondered what are the differences between “4-stroke engines” and “2-stroke engines” when these terms are mentioned in an advertisement? As the engine is considered an important part taken into consideration when deciding to buy a motorcycle, PTT Lubricants will introduce you to the differences between the two types of engines to make it  easier for you to decide which one suits your needs better , in terms of the  use and maintenance.

For the 4-stroke engine, it is called 4-stroke because the engine has to work in 4 strokes to complete 1 cycle. The 4 strokes include  intake, compression, combustion  and exhaust. Meanwhile, a 2-stroke engine  works more quickly since it combines  the intake and compression into 1 stroke, and the combustion  and exhaust into another one. 

In addition, the two types of engines also differ in 4 main points as follows:

1. Size of cylinder block

A 4-stroke engine is generally larger than a 2-stroke engine due to the number of parts in its  internal system , such as  a valve operating system or a timing chain, etc. A  2-stroke engine, on the other hand, does not have a valve operating system. It only has the exhaust pipe. Hence, the smaller size of the engine.

2. Air intake pipe

Unlike in a  4-stroke engine where the air intake pipes are on the same level, the air intake pipe from the carburetor of a 2-stroke engine is not positioned on the same level. 

3. Combustion and lubrication system

Most 4-stroke engines will not emit white smoke due to the complete combustion and the absence of  engine oil combustion,  thus fewer problems regarding white smoke. A  2-stroke engine, on the other hand, is more likely  to emit white smoke. Therefore, it is advisable  to use a specific formula engine oil (2T engine oil) mixed with fuel (Pre-mixed and Autolube) to help lubricate the internal parts of the engine and be combusted along with the fuel without causing white smoke.

4. Engine sound

Unlike a 4-stroke engine that has a softer and deeper sound, a 2-stroke engine has a rather squealing sound. We can observe the difference of the sound when the engine is started.

Pros and cons  of 4 stroke engines and 2 stroke engines

2-stroke engines have the advantages of quick start , better acceleration and fewer parts which are  easier for maintenance. 2-stroke engines can also be very powerful even without  much engine modification . However, a 2-stroke engine emits more pollution and white smoke, has a loud engine and consumes more fuel due to the lower combustion efficiency from the contamination of the residual exhaust in the combustion chamber.  2-stroke engines also have  a relatively high engine wear rate and bad cooling power, resulting in a shorter service life.

4-stroke engines have advantages in fuel economy, smooth operation with low noise while driving, easy maintenance and engine modification . 4-stroke engines are  also better at completing combustion, therefore, emitting less white smoke and pollution. However, since there are more parts and complexity in the system of the engine, the maintenance cost is also higher.

That is it for the differences between a 4-stroke engine and a 2-stroke engine as well as their advantages and disadvantages! We hope it will be useful to anyone who is buying a motorcycle. And don't forget to choose high quality engine oil from PTT Lubricants, available now at PTT Station and FIT Auto, or any stores that hold PTT Lubricants products near you.