How Fast is a Dirt Bike

When you think of a dirt bike, speed is usually not the most important factor you’ll be looking at. 

However, it’s a good thing to know – especially if you know some places where you can really open it up. 

Dirt bike speeds will depend on a variety of factors, but the engine size is the major contributor. 

Use this page to get an idea of how fast a dirt bike can go based on its engine’s CCs.

How Fast Can a Dirt Bike Go?

A dirt bike’s lightweight frame, suspension, engine size, engine design, fuel delivery, cooling system, gearing, and tuning all contribute to its top speed. 

In general, a two-stroke engine will have a little more power than a 4-stroke of the same size. 

How fast you’ll be able to get a particular dirt bike will also depend on where you’re riding it and your weight. 

Comparing estimated top speeds by engine size can be a good place to start. 

Refer to the table below to learn how fast the typical dirt bike can go by engine size. Continue reading for more details on dirt bike top speeds. 

How Fast Does a 450cc Dirt Bike Go?

450cc dirt bikes are typically the largest engine size you’ll find. 

A 450cc dirt bike has a top speed range of 80 to 110mph.

These are also generally the fastest types of dirt bikes. 

How Fast is a 250cc Dirt Bike?

A 250cc dirt bike is a great size for a wide variety of riders. 

These bikes will generally have a top speed of up to 80mph.

How Fast is a 150cc Dirt Bike?

 A 150cc dirt bike will usually be able to go anywhere from 50-60mph.

How Fast Does a 100cc-110cc Dirt Bike Go?

A 100cc dirt bike or 110cc dirt bike will typically have a top speed of around 40-50mph.

How Fast Does a 40 to 70cc Dirt Bike Go?

Smaller displacement dirt bikes are a great starting point for beginners and kids. 

Smaller engines are less powerful, and generally have lower top speeds. 

You can expect a 50cc dirt bike (or something in the 40-70cc size range) to have a top speed of 30 to 40mph. 

What is the Fastest Dirt Bike in the World?

The fastest dirt bike is the KTM 450 SX-F, with a top speed of about 123mph. 

Most of the world’s fastest dirt bikes have top speeds ranging from 110 to 120mph. 

We’ll break down some of the fastest models out there. 

Of course, there are some things you can do to make your dirt bike faster too. Continue reading below. 

How to Make Your Dirt Bike Faster

If you want, you can always tune a particular bike to go faster. 

First, the easiest and cheapest way to ensure your dirt bike can go as fast as possible is to keep it in tune and well maintained.

Refer to your bike’s service manual and stick to the recommended scheduled maintenance and inspection routine. 

This would include:

• Tuning the ignition timing. 
• Cleaning or replacing the air filter.
• Changing the oil and oil filter. 
• Cleaning and syncing the carbs. 

You can also use better fuel in your gas tank to improve performance. 

After that, you’ll need to start swapping out parts in order to get more speed. You main options include:

• Swapping out for an air filter that allows more air flow. 
• Installing a race clutch. 
• Porting the engine. 
• Installing a new camshaft. 
• Increasing the cylinder and piston sizes. 
• Upgrading the exhaust. 
• Rejetting the carbs. 
• Changing the gearing. 
• Improving the suspension. 

Note that all of these modifications require some knowledge of motorcycle maintenance. You’ll also need to retune your engine when changing one of the components. 

For more complicated upgrades like ports or cylinder boring, you’ll need the help of a qualified machine shop.