YZ250 Top Speed

Ah, the classic Yamaha YZ250. This was my first ever dirt bike. Naturally, as a dirt bike rider, I had to know what the YZ250 top speed was.

Here’s my YZ250 on the first day I rode it:

In this post, we’ll cover the YZ250 top speed and many of the factors that can impact or change the top speed of a YZ250.

YZ250 Top Speed

Yamaha had a rich history in musical instruments before its first off-road dirt bike was released in the mid-1950s. 

If you’re a 2-stroke, or Yamaha, fan, it almost seems like they haven’t really updated their 2-stroke models since the 1950s…

I’m joking — partly…

The YZ125 did see an update in 2022, but prior to that, the 2-stroke dirt bikes from Yamaha had been mostly unchanged for years and years.

It hasn’t always been this way, but today, many people are starting to think of Yamaha as having the fastest machines. At least in the motocross racing world.

What does this mean for the YZ250 top speed?

The YZ250 top speed is about 75-80 mph.

This is about 15-20 mph faster than the YZ 125 top speed, the cousin to the YZ250. It’s also about 5-10 mph slower than the top speed of a CRF450R.

Why did I pick these two machines to compare the YZ250 to?

I picked the YZ125 because it is a very similar bike to the YZ250. I also own a brand new 2023 YZ125 and it’s nearly identical to the YZ250 — the biggest difference is the engine. Everything else, chassis-wise, is pretty much the same.

The CRF450R is considered to be a “comparable” bike when comparing 2-strokes and 4-strokes. Back in the day of motocross racing, the rules allowed 250 2-strokes and 450 4-strokes to race each other as the power is similar. Today, those rules have changed a bit, but the two bikes are still similar in power and make for a good comparison.

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What impacts the top speed of a YZ250?

As dirt bike riders, it’s inherent in our nature to want to know how fast our bikes go. Really, most motorheads want to know how fast their vehicles go, whether it’s cars, trucks, snowmobiles, or something else.

That said, it can sometimes be difficult to know the true top speed of a dirt bike. The reason for that is that there are so many variables that go into determining the top speed.

Let’s look at some of the items that impact the top speed of a YZ250.

Modifications

Modifications and after-market parts are the items that impact the YZ250 top speed the most. If your YZ250 has a bunch of engine work done to it, a pipe, reeds, and more, that’s not comparable to a stock YZ250.

A stock YZ250 top speed will be significantly less than the top speed of a YZ250 with a ton of work done to it. After all, you bought and installed those aftermarket parts to make the bike faster, right?

Hundreds, if not thousands of dollars spent, I’d hope the modified bike goes faster…

The more work that’s done to the bike, the more the top speeds are going to differ.

Here is my YZ250 with the engine out getting some work done:

You might be thinking, “okay, that makes sense, but what is the YZ250 top speed before I make any mods to it? How fast does it go when I get it from Yamaha?”

If that’s what you’re wondering, it’s a bit easier to answer, which we answered above, but there are still more variables to consider, such as gearing, riding conditions, the rider, and more.

Gearing

The item that has the second largest impact on the YZ250 top speed is the bike’s gearing.

For those unfamiliar, gearing refers to the size of the front and rear sprockets, specifically the relationship between the two.

For reference, the stock gearing for this bike is a 14-tooth front sprocket and a 50-tooth rear sprocket.

Riders choose different gearing based on the conditions they’re riding in. If the rider is racing supercross, they generally want more acceleration (known as more bottom end). To do this, they’d use a smaller front sprocket or a larger rear sprocket. This is a low gear ratio.

If the rider is racing motocross, they may want more top speed (known as top end). To do this, the rider would use a larger front sprocket or a smaller rear sprocket, which is a higher gear ratio.

Riding in the woods would require even yet another gearing combination, different than that of supercross and motocross.

This may sound like a small thing to some, but it has a huge impact on the top speed of a YZ250 (any dirt bike, really). Depending on the gearing changes, it can increase or decrease the YZ250 top speed by more than 5-10 mph.

A bike that has a 10-tooth front sprocket instead of the stock 16-tooth sprocket is going to have a different top speed. (I made the difference wide to make a point — no one is running a 10-tooth front sprocket on their YZ250…)

Also, changing the front sprocket has a larger impact, or greater change, on the bike’s speed and bottom end than changing the rear sprocket. Going up or down one tooth on the front sprocket is not equal to one tooth on the rear sprocket.

Changing the front sprocket by one tooth is equivalent to 3-4 teeth in the rear.

Riding Conditions

Another factor that can impact the YZ250 top speed is the riding conditions. This can be the location where you’re riding and the conditions of what you’re riding on.

For the location, are you riding at sea level or thousands of feet above elevation? Generally, dirt bikes produce more power closer to sea level than at high levels of elevation. Of course, this will impact the top speed of a YZ250, as it would, and does, any dirt bike. Anything with an engine, really.

If you’re riding in a state where you’re way above sea level, your YZ250 top speed is going to be lower than if you’re riding at sea level.

Also, for the location, are you riding in the woods, on a motocross track, or on a paved road? Are there hills or is it flat?

If you’re riding in the woods, your YZ250 top speed might be limited by trees or other obstacles (mud, train tracks, logs, etc.). If you’re on a motocross track, you can only go as fast as the track layout allows.

This type of location consideration also impacts the conditions of what you’re riding on. If you’re riding on a flat paved road your YZ250 top speed is going to be entirely different than if you’re riding on a tight, sandy racetrack or in the woods with a lot of trees.

Rider

The rider on the bike also impacts the top speed of a YZ250. This has an impact on the top speed for two reasons: 1) their size/weight, and 2) their ability.

First, let’s look at the rider’s size and weight. Someone who weighs 300 pounds is not going to be able to go as fast on the bike as someone who weighs 125 pounds. The top speed of a YZ250 is going to go down the heavier the rider is.

In this weight example, the lower rider’s weight is less than half of the heavier rider’s weight. The YZ250 top speed will not be cut in half, like the weight, but it will still be impacted. Also, a 125-pound rider probably isn’t riding a YZ250 — although they could…

Someone who is a skilled rider can likely get the YZ250 top speed to be a bit higher than someone who is brand new to riding. A rider who can quickly and smoothly shift through the gears can hit a higher top speed on a YZ250 than someone who is just learning how to use a clutch.

Plus, someone who is just learning how to ride might be a little nervous (scared, frankly) to really run the bike wide open to hit its top speed.

Take pro motocross and supercross racer Ken Roczen as an example. Not only is he just light, but he is also very skilled. The top speed of a YZ250 with Ken Roczen riding it is a bit higher than a brand-new rider and weighs 250 pounds.

If you’re simply doing a drag race on pavement in a straight line, the skill level may not have as big of an impact, but the weight still will. The weight will also impact the bike’s ability to get to that top speed.

Other Items Impacting the Top Speed of a YZ250

A few other items that will impact the top speed of a YZ250 are the condition of the bike, riding weather, and how the top speed is being recorded.

A bike that hasn’t had maintenance kept up on it or has issues and isn’t running properly won’t be able to reach the peak top speed that the bike is capable of. The top speed of YZ250 which is maintained very well and running perfectly will be faster than that of a bike that is not taken care of and running like poorly.

Similar to location, the weather you’re riding in can have an impact on the YZ250 top speed. If you’re riding in the rain, causing the pavement to be wet, the top speed is likely going to be lower than it otherwise could be.

If the motocross track is super dry due to a lack of watering or rain, you might not have much traction, and therefore the bike likely wouldn’t reach its top speed in those conditions.

Also, the temperature you’re riding in can impact the top speed of your bike because it can impact how the bike is running.

For example, since the YZ250 is still carbureted, if the bike’s carburetor isn’t running right, that bike is going to have a lower top speed than one with its carburetor jetted properly and running right.

The final item we’ll mention that can impact the YZ250 top speed is how the top speed is being recorded.

Technically, this doesn’t change the top speed the bike is actually going – it only changes what you think it is.

If you record a bike as going 50 but it’s really doing 80, that doesn’t mean the bike did 50. It did 80, you just recorded it inaccurately. I digress…

If you are recording the top speed of a YZ250 with an onboard GPS, that’s likely going to be more accurate than someone pointing a speed gauge at you as you go by.

Waving the Checkered Flag on the YZ250 Top Speed

When it comes down to it, most people just want to know how fast their bike is capable of going. All the mods and items covered above are important and impact how fast their bike goes, but, most people would be satisfied with simply knowing how fast, roughly, their bike is.

Is it 30 or is it 80? It doesn’t really matter if it’s 81 or 82 instead of 80, but roughly how fast is it?

In that case, the YZ250 top speed is about 75-80 mph.

Frequently Asked Questions About the YZ250 Top Speed