Speed Check: How Fast is 125cc ATV in Real-World Tests? (2023)

For those curious about the capabilities of and how fast is 125cc ATV (all-terrain vehicle), you’re in the right place. 

I’ll delve into its speed both in MPH and KPH, unpack the significance of ‘125cc’, gauge its power, and question its adequacy. 

Further, I’ll explore weight limits, choosing the right engine size, and tips to maximize speed. 

Let’s break it down.

How Fast 125cc ATV? In MPH & KPH

A 125cc ATV can achieve a top speed of 40 to 50 miles per hour (64 to 80 kph) 

Depending on circumstances and rider preferences, its speed can be adjusted down to 10 mph, and in some rare cases, even as low as 5 mph. 

It’s important to note that while 125cc ATVs are often recommended for older teens and adult beginners, youth ATVs come equipped with speed limiters to ensure safe riding and speed management.

What Does 125cc Mean?

“125cc” actually refers to the cubic centimeter capacity of the engine’s combustion chamber.

Meaning, the engine where the combustion takes place.

This includes ATV’s, motorcycles, or any other combustion engine. 

Narrowing down, “125cc” means the engine has a cylinder volume of 125 cubic centimeters.

This indicates the engine’s displacement i.e. a factor in determining its power and performance capabilities. 

Rule of thumb, the larger the cc value, the more powerful the engine.

Note: Design and tuning of the engine will also play a factor.

Source: Quora

How Powerful is a 125cc ATV?

The power of a 125cc ATV is dependent on a few different factors.

Such as design, make, model, and engine tuning.

A 125cc ATV engine produces roughly between 7 to 10 horsepower.

Such a power range is suitable for light trail riding, flat terrain cruising, and beginner’s to get some good riding experience.

A 125cc quad offers a decent amount of power, but it isn’t as powerful as larger ATV’s designed for farm work, intense off-roading, or adult riders.

Ideal the ATV’s power will match the ATV’s intended purpose, and the rider’s skill level.

Is a 125cc ATV Fast Enough?

As mentioned above, I think this largely depends on the ATV’s intended use and the riders expectation and ability.

For Beginners/Younger Riders: A125cc ATV would be considered ideal.

The speed and power would be manageable, which allows the rider to learn and gain confidence without the intimidation of excessive engine power.

Recreational Riding on Flat Surfaces: 125cc provides an ideal range of speed and power for leisurely riding and and gentle trails.

Intense Off-Roading or Racing: Challenging terrains, involving jumps, or competitive racing, will require more more power.

A more ideal range for off-roading and competitive racing would be between 250cc and 450cc.

Heavy Loads or Towing: If you plan on carrying or towing heavy loads, I’d advise aiming more toward the 500cc mark and above. 

For such duties – 125cc engine will not get you far.

125cc ATV Weight Limit – How Much Weight Can It Hold?

The weight limit of a 125cc ATV can vary on such factors as make, model, design, and ATV build.

I have a general guideline:

A 125cc ATV can typically accommodate a range from 300 lbs to 400 lbs (136 kg to 181 kg).

This weight includes a the combined weight of the driver, passenger, and any other cargo on board.

Choose the Right ATV Engine Size

ATV Engine SizeIdeal Use
50ccYoung beginners, light trails
90ccYouth riders, introductory trails
125ccLight recreational, beginner
250ccIntense off-roading, racing
300-450ccChallenging terrains, racing
500cc and aboveHeavy loads, towing, utility

How Can I Increase the Top Speed of My 125cc ATV?

Many 125cc owners get their ATV when they are young and simply outgrow it or would like to improve it top speed. 

I’ll provide a range of different ways you can modify your ATV to increase its speed. 

Changing Tire Dimension

Installing larger tires is a good way to give your ATV’s top speed a boost. Bigger tires increase the circumference – meaning, they cover more ground with each spin. 

Related: Demystifying ATV Tire Size Meaning: What You Need to Know (2023)

If you’re thinking of going more than a couple of inches up in tire diameter, I’d recommend considering an accompanying clutch kit.

Without this, you may lose some power.

Changing The Gearbox Gearing Ratio

Changing up the sprocket sizes can be a game-changer for your increasing your top speed. 

Opt for a larger rear sprocket or a smaller front one, and you’re pretty much giving yourself a shot at a higher top speed. 

This might influence how quickly you can go from 0 to 60 – a smaller sprocket could potentially make acceleration smoother.

Installing a Racing Clutch

You may want to invest in a racing clutch.

You can tweak dimensions and effectively tune your top speed to match your speed as you wish.

Improving the Engine Power Output

Enhancing the engine’s power output can naturally lead to an increase in the ATV’s top speed.

Upgrades such as a high-performance exhaust, air intake, or engine tuning can contribute to higher speeds.

Removing the Speed Limiter

If your ATV comes with a speed limiter, disabling it can be an effective way to unleash higher speeds.

Make sure you’re aware of the legal implications and follow regulations. 

For electronic speed limiters, reprogramming the bike’s ECU can remove the limit.

Mechanical limiters can often be removed with careful disassembly.

Changing the Gear Ratio

If your ATV features an open sprocket and chain system, altering the gearing ratio can have a significant impact on top speed for your ATV.

Increasing the size of the front sprocket while reducing the size of the rear sprocket can yield higher speeds.

Adjusting the gear ratio can be particularly beneficial for specific racing tracks where different top speeds are required.

Reflashing the ECU

By reprogramming the bike’s ECU (electric control unit), you can potentially remove these limiters. 

Some riders have reported achieving speeds of up to 100 mph by flashing new software to their ATV’s ECU. 

Keep in mind that different models may have different stock top speeds and limiters, so research is crucial.


To wrap it all up for you. 

The ATV engine size you choose should should be based on your skill level and the intended use for the ATV.

Engines can range from 50cc to 500cc+, ranging from suitable to youth drivers for introductory trails, to heavy duty towing and carrying machines. 

I wish you the best in making your choice.

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