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Yamaha YZ125 Top Speed, Specs and Features (Explained)

Yamaha Motor is a world-renowned motorcycle manufacturer company. They are extremely popular for their high-performance bikes. From race tracks to dirt trails, their bikes are everywhere. There will be a particular bike from them that you will always notice on any dirt trail. That is the YZ125.

The beginning model of Yamaha’s dirt bike series, the YZ 125, is an outstanding bike. The two-stroke engine on this bike makes it a flying machine. In contrast to any of us, this bike knows how to handle all the bumps anyone can encounter in life, thanks to its powerful engine, effective cooling system, and smooth fork.

Here in Yamaha YZ125 Review, we will be examining this fantastic bike made by Yahama Motors. We’ll look at its features as well as its pros and cons. Furthermore, we will also give you some suggestions on making this already perfect bike even better. Alright, let’s begin.

About Yamaha YZ125

In 1974, the first model of Yamaha YZ125 came out. The frame of the Yamaha YZ125 remained the same from its inauguration to 2004. A single backbone made of steel was available in the frame. As Yamaha used steel, these versions of the bikes were heavier than the later versions. On average, the steel version weighed roughly around 80-90 kilograms.

Yamaha’s quest to make the bikes lighter made them move to an aluminum alloy frame. They changed the steel backbone to an alloy one. The material change made a significant difference in the bike’s weight, decreasing roughly 4 kilograms. However, Yamaha wanted even lighter, and therefore, they switched to a new fork design and wheel assembly in 2008. As a result, the bike was even more lightweight than 86 kilograms.

The bike has a two-stroke engine that uses reed valve induction, and its displacement is 125cc. The initial model of the motorcycle was air-cooled. We are talking about those models from 1974 till 1980. However, after that, Yamaha switched to liquid cooling in 1981. If you are wondering about the horsepower, it has 35 HP. Don’t be fooled by this low horsepower, as this bike is mighty and has won multiple AMA National Motorcross Championships.

Yamaha YZ125 Specs and Features:

1. It’s a Two-Stroke Thing

This bike has a 125 cc engine. The engine is two-stroke, which will create more torque when the rpm is high. In fact, this engine is more powerful than four-stroke engines.

To maintain the heat of this powerful engine, Yamaha used liquid cooling so that the engine doesn’t overheat, ensuring the acceleration is much better. Additionally, the performance will be sublime in case of any mid to high rpm level.

2. A Lighter Frame

The frame of this bike is light. This frame is made from aluminum alloy and designed to be race-ready. Hence, this bike has been used in several races. The aluminum used here gives the right amount of integrity.

Consequently, this cradle frame which is semi-double will be both solid and flexible at the same time. Trail riding can be extremely rough, and therefore, this frame is perfect for any adventure you have in your mind.

3. Braking System with High Performance

Trail riding is highly dependent on braking. If the brake fails, death is even a possibility. For this reason, outstanding braking system so that you can remain safe. The front brake of this bike is a 270mm Hydraulic Disc brake.

On the other hand, the rear brake is a 240 mm Hydraulic Disc brake. These brakes will allow you to stop the bike at any given speed really fast. Aside from that, feel is also present. Moreover, these brakes greatly benefit from reducing unsprung weight in your light vehicle. That means more speed!

4. Chassis Designed for Riders

By looking at the chassis’s design, you can tell this bike has been made with riders in mind. This chassis has an ergonomic design and is highly rider-friendly to experience less fatigue.

The chassis on this bike is so well-tuned that moving and handling are effortless. Experienced riders will find this bike to be incredibly fun to ride. Furthermore, it can give you the confidence for those bigger leaps if you are still learning. 

5. KYB Fork – Industry-Leading

You will love what Yamaha has used for the fork. The invented KYB Fork is meant to give you outstanding comfort and performance. With a speed-sensitive system and leaf spring, this fork has a speed-sensitive system.

The mid-speed valve is equipped with this leaf spring. Therefore, it will provide more accurate damping. There are 11.8 inches of travel in this fork, which will surely make your ride a lot smoother. You will notice how easy it is to jump too.

6. A New Exhaust System

Compared to the previous YZ125, the new one has a different exhaust. This is due to Yamaha going a different route with the exhaust. It has a brand new expansion chamber.

Furthermore, the exhaust muffler has also been designed differently. Having gone on a diet and lost fat, it is smaller now. Moreover, the system looks slender and more attractive.

Yamaha YZ125 Top Speed

The maximum speed you can get from a Yamaha YZ125 is 70 miles per hour. In terms of kilometers, this is over 112 kilometers per hour. For a bike that has a 125 cc engine, this speed is indeed quite impressive.

Nevertheless, speed can vary based on the model year. Several times in the past, the YZ125’s weight was reduced or increased. These weight changes have significantly affected the beast’s top speed in either a positive or negative way.

As of the new model year of 2022, the top speed of the YZ125 is 70 mph. Using its two-stroke 125cc engine, you can leave your competitors in the dust. Its astonishingly fast engine is largely due to its reed valve induction system. This bike will move like a demon with strong mid-range acceleration and an unbelievable bottom end.

How to Increase the Yamaha YZ125’s Top Speed?

The Yamaha YZ125 is an excellent machine. Riding this bad boy is fun and exciting. However, who doesn’t like a bit more extra fun? You have mod for this purpose.

Choosing from many different mods on the market today can enhance your dirt biking experience. Are they expensive? Maybe not ultimately, but you will be glad you did!

In the next section of the Yamaha YZ125 Review, we will give you a few suggestions regarding how you can make your YZ125 even better. So let’s begin!

1. 144cc Kit:

Officially from Yahama, you can get a 144cc kit to increase your 125cc engine to 144cc. Available at GYTR, this kit can increase your horsepower from 35 to 40, which is a significant bump.

This kit is made by Athena and works perfectly with YZ125. If you are into competitions, upgrading your bike to 144cc can be good. However, keep a few things in mind, such as the rev and the vibration.

Compared to the 125cc version, the 144c version will not rev as high, and you will notice more vibration. Also, starting will take a bit longer time.

2. Upgraded Valve System:

Adding a V-Force3 Reed system to your YZ125 can be one of the best decisions you have ever made. Your bike will have increased power and improved throttle response from this valve.

Aside from that, you will have a higher rev compared to the stock system. Also, this valve system is more durable than the stock.

3. 13/49 Gear:

Two-stroke engines are not usually ideal for beginners. However, you can mod the gearing in a way that can help you to get more out of the engine. The bike can be more controllable by upgrading the gears to 13/49 from 13/48.

Additionally, if you’re used to riding four-stroke engines, this mod is ideal. You’ll feel a better response when you twist the throttle. You can also increase your speed from the midrange.

Yamaha YZ125 – Pros and Cons:


  • Fun to Ride:

No matter who you ask who already rides this bike, they will all agree on one thing, that it’s fun. Your sense of joy will arise from both the sounds of the bike as well as its feel.

You will get the adrenaline you need to continue doing more laps when starting this bike. Most users say that riding this is more fun than riding a four-stroke engine. That makes sense since two strokes are more powerful.

  • Engine Power:

Another pro of this bike is that the engine’s power is quite high. Whenever you are going to ride this bike, you will understand what this bike is capable of doing. No wonder why this is so fun! This bike can do whatever you tell it to, from jumps to speeding.

With its powerful two-stroke engine, it has no problem handling any stress. When the stress gets higher, and the engine starts to heat up, there are no worries as the liquid cooling system will address the problem effectively.

  • Balanced Weight:

Another significant fact about this lightweight bike is it’s perfectly balanced. Light bikes can fly off the trail when they have high power. This bike doesn’t have that issue. Despite being lightweight and powerful, the balance of the weight will keep you on track.

For this reason, you will see this bike in a lot of competitions. The bike’s chassis is designed to give you complete confidence when riding. And, of course, this bike won’t leave you feeling fatigued after riding for an extended period.

  • Superior Handling:

According to some riders, this is the best handling bike globally. Of course, you are going to have to decide that for yourself. Even so, we can’t deny the fact that this bike handles quite well.

You can do no matter what you would like with this bike. Thanks to the agile handling of this bike, you’ll be able to take tight corners quite easily. On top of that, you can ride this forgiving bike on any dirt trail. Experience is necessary for tough trials.

  • Low-Cost Maintenance:

This dirt bike does not require extensive maintenance compared to other dirt bikes. The top-end needs to be replaced frequently, but that won’t break your budget. About $150 should be enough for the job.

Compared to a four-stroke engine that would cost around $800, this seems like a bargain. Also, two-stroke engine mods are pretty cheaper too.


  • Not Ideal for Beginners:

This bike is not ideal for anyone who has just started dirt biking. The bike is too powerful, and it cannot be very safe. Even though this bike is excellent at controlling and handling, anyone with passive experience can get into trouble. The fun will be at its highest if you are experienced enough to ride this bad boy.

  • No Bottom End:

Another notorious fact of this bike is that it doesn’t have any bottom end. You will be able to go from middle-range to higher range, but you won’t be able to get to the bottom. As a result, controlling this bike at some point could be quite challenging since you cannot control the speed very well at the lower end.

Frequently Asked Questions:

How fast does a YZ125 go?

The max speed of YZ125 is 70 miles per hour which is as much as 112.654 kilometers per hour. For any dirk bike, this speed is really impressive. The bike has a powerful two-stroke engine and can quickly get off very high speed. Additionally, the liquid cooling makes the engine remain cold and calm. Hence, you won’t lose much of the pace going through the trails.

What does a 2006 YZ125 weight?

YZ125 models from 2006 weigh approximately 197 pounds. This bike is closest to the AMA weight limit. How Yamaha managed to limit the weight of this light is extremely impressive. Most of the credit goes to the aluminum alloy frame that it has. This frame is exceptionally light yet extremely strong. Do all the jumps you would like, yet the structure will not lose its integrity. The newer models of the YZ125 are a bit heavier since they feature new internals. A 2022 model should weigh approximately 209 pounds, increasing around 12 pounds compared to a 2006 model.

How fast does a two-stroke engine go?

There is a speed range between 55 and 75 mph for two-stroke engines. On the other hand, Four-stroke engines can reach speeds of 45 mph. Nevertheless, it would be best to consider the terrain you are riding on to determine the speed you can achieve with a two-engine.

You can hit 75 mph if the terrain is straight and smooth. On the other hand, a bumpy road will undoubtedly decrease your speed considerably. As a result, how fast you’re going on a road you’re riding is more relevant than how powerful your engine is.


Legends say life is messy; when on the bike, it is easy. You will understand that is true when you ride the Yamaha YZ125. This great bike is a funhouse and will give you the best adventure of your lifetime. This lightweight dirk bike’s outstanding two-stroke engine will do all the magic needed to be done.

Kudos to Yamaha for making this bike a perfect riding machine. Excellent for getting into the dirt biking game, this bike is incomparable. Yes, it can be pretty intimidating as it lacks the lower end. However, that’s the only trade-off you need to do. That’s not much when it comes to extra fun.

We tried to cover everything you need to know in Yamaha YZ125 Top Speed, Specs, and Review. The YZ125 is a beast, and if you are considering getting one, we can assure you that you are not making a mistake.

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