Two Stroke vs Four Stroke: Pros & Cons

When you’re looking to buy a motorcycle and found several units you like, do you go with a two-stroke or a four-stroke engine? 

For those of you who are new to the motorcycle world, here’s a quick guide to the basics of 2-stroke engines vs 4-stroke engines. 

What is a Stroke?

A stroke in an engine is the movement of the piston from one end of the cylinder to the other, either on the up- or down- stroke.

• Intake stroke: Air and fuel are drawn into the cylinder.  
• Compression stroke: The piston squeezes the fuel and air inside the cylinder. 
• Power stroke: The compressed fuel-air mix is ignited. 
• Exhaust stroke: The leftover gases are pushed out of the cylinder, and then it starts all over again with the intake.

In a four-stroke engine, the piston moves down and pulls in air and fuel (intake stroke); then the piston goes up in the cylinder and compresses the fuel and air (compression stroke); then ignition happens and pushes the piston down (power stroke); and finally the piston moves up again to push out the exhaust gasses (exhaust stroke).

On a 2-stroke engine, two of those strokes happen in one movement of the piston. The intake and the exhaust happen as the piston moves from top to bottom, and compression and ignition happen as the piston moves up toward the top of the cylinder.

Four-Stroke Engine Pros & Cons

Pros

• Broader powerband, which means less shifting
• Less maintenance required

Cons

• Heavier than a two-stroke engine
• More expensive to repair than a two-stroke

Two-Stroke Engine Pros & Cons

Pros

• Lighter, faster, more compact than a four-stroke engine
• Less moving parts

Cons

• Narrower powerband, which means more shifting
• More maintenance required

A 125cc two-stroke dirt bike will pack about the same punch as a 250cc four-stroke, so for every CC you add, you get about twice the power. However, the narrow power band of a 2-stroke might not be suitable for inexperienced riders who don’t want to shift all the time. 

Two-Stroke vs Four-Stroke: Which to Choose

The first thing to consider when deciding between a 2-stroke and a 4-stroke bike is how much you want to shift. If you don’t want to be shifting all the time in the narrow powerband of a two-stroke, then a four-stroke is the way to go. 

If you’re looking for a light, punchy bike and you’re not afraid to get your hands dirty with a little more maintenance, the two-stroke might be the right choice for you. Both have their pros and cons, so the choice depends on what you’re looking for in the motorcycle and what type of investment you want to make on it when it comes to ongoing maintenance.