KX65 top speed in white text with image of Kawasaki KX65 dirt bike on green background

James Stewart

KX65 Top Speed: Fast Enough, or Too Fast?

Kawasaki, Top Speed

Everyone who owns a dirt bike wants to know how fast it goes – including you (and me). Doesn’t matter how old you are, where you’re from, or what your bike is. You want to know. In this post, we’ll look at the top speed of KX65.

Whether you’re a young racer wondering how fast your KX65 is that your parents bought you, or if you are the parent who is purchasing this bike for your kid and you’re wondering what the top speed of KX65 is, we will be covering that here in this article.

Kawasaki KX65 dirt bike with Dirt Bike Vault logo

KX65 Top Speed

Kawasaki has long been one of the dominant players in the dirt bike world, especially in the youth motocross bike world, with bikes such as the KX65.

What does this mean for the KX65 top speed?

The KX65 top speed is about 45-50 mph.

This is about 10-15 mph slower than the YZ85 top speed. It’s also about 5-10 mph faster than the CRF80 top speed.

Why did I pick these two bikes to compare the KX65?

First, the YZ85 was picked because 85cc dirt bikes are a natural progression for kids moving on from a 65cc dirt bike. There isn’t really much for race bikes in-between. After 85s, many kids move on to 125s, then 250s, and so on.

For the CRF80, I chose this one to compare it to because it’s a similar size engine, but as a 4-stroke (and a Honda, of course). People are often interested in how similar-sized bikes compare when looking at 2-stroke versus 4-stroke. The CRF80 is more of a trail bike, while the KX65 is a race bike, usually, but they’re still similar in engine sizes.

I’ll throw one more comparison in for you, which is Kawasaki’s KX100. The KX65 is about 15-20 mph slower than the KX100.

What changes the top speed of KX65?

It can be tough at times to calculate the true top speed of a dirt bike because there are quite a few different items that can impact it. Let’s take a look at them.

Engine Work and Aftermarket Parts

This might be obvious to some, but engine work and aftermarket parts are going to impact the KX65 top speed. Arguably, most of anything.

If your KX65 has engine work (especially a big bore kit) and a pipe, that’s not really comparable to the top speed of a stock KX65.

The top speed of KX65 that hasn’t had any work done to it will be significantly lower than the top speed of KX65 that has undergone mods.

The more work you do to the bike, the greater the difference in speeds will be. You paid to make the bike faster after all, didn’t you?

There are other factors at play here too – such as gearing, riding conditions, and more.

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The second most important factor in determining the KX65 top speed is its gearing. Gearing refers to the size (and ratio) of the front and rear sprockets.

For reference, the stock gearing for this bike is a 13-tooth front sprocket and a 47-tooth rear sprocket (depending on the year of your bike).

Riders normally pick different gearing depending on the situation they’re riding. If the rider is racing supercross, they would typically want more acceleration (referred to as more bottom end). To achieve this, they’d use either a smaller front sprocket or a larger rear one. This is known as having 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; in other words, they would be changing to a higher gear ratio.

Riding in the woods can require an entirely different gearing combination than that of supercross or motocross.

This might not sound like much to some people, but it has a large impact on the top speed of KX65 (or any dirt bike, for that matter). Depending on the gear changes made, it can increase or decrease the KX65 top speed by more than 5-10 mph.

A KX65 with a 6-tooth front sprocket will have a different top speed than one with the stock 14-tooth front sprocket (I made the difference wide to make a point — no one is running a 6-tooth front sprocket on their KX65….).

Additionally, a change to the front sprocket has a great effect on the KX65 top 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.

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

Rider: Size and Ability

The top speed of KX65 is going to be slower if the rider weighs more because it takes more work from the bike, while the bike and engine maintain the same ability/capacity. The heavier the rider, generally the lower the KX65 top speed is going to be.

In addition, an experienced rider can make the KX65 go faster than a beginner who is just learning. A rider who knows how to quickly and smoothly shift gears can hit a higher top speed than someone who is just learning how to use a clutch.

Consider Adam Cianciarulo back when he was a kid on 65s. He can hit a faster top speed on a KX65 than a kid who is just learning how to use a clutch. 

Riding Conditions

The KX65 top speed can also be impacted by riding conditions, including both location and surface.

For example, a dirt bike’s power output is generally higher closer to sea level than at high altitudes. So if you’re planning to ride your KX65 in the mountains, it will likely have a lower top speed than if you were riding at sea level.

Even if you’re not necessarily in the mountains, but you’re just riding in Colorado, as an example, you’re much higher above sea level than the coasts of the US. That will cause your KX65 top speed to be lower.

Smaller-size bikes (bikes with small cc engines) are more impacted by elevation changes than larger bikes, too. For example, a KX65 top speed is impacted more by elevation than the top speed of a CRF450R.

Are you riding in the woods, on a motocross track, or on a paved road? If it’s in the woods, your top speed might be limited. If you’re racing motocross, you can only go so fast while remaining safe and within bounds (and, don’t forget, sometimes slow is fast).

Apart from the elevation and location, another factor that affects the KX65 top speed is the surface on which it is being ridden. The top speed of KX65 ridden on flat pavement will be different than if it were driven on a tight, sandy motocross course; even the type of tires can make a difference.

A Few Other Factors that Can Impact the KX65 top speed

Your KX65 top speed can also be impacted by a few more things, including the condition of your bike, the weather, and how you’re recording the data.

A bike that is regularly maintained will run faster and more efficiently than one that isn’t. For example, a KX65 that has had consistent maintenance done to it will be able to reach a higher top speed than one not taken care of properly.

The weather and temperature can both affect your KX65 top speed. If it rains, the pavement will be wet and your top speed will probably be lower than normal. Similarly, if it’s an abnormally cold or hot day, that could impact how well the bike is running, which could then lower the top speed.

If you want to get an accurate reading of the top speed of KX65, use an onboard GPS device rather than relying on someone pointing a speed gauge at you as you zoom past. This doesn’t mean the bike will actually go any faster or slower, it just changes what you end up seeing on paper.

Waving the White Flag on the top speed of KX65

As we pass by the white flag of this article and enter into the last lap, we want to summarize what we’ve covered so far.

Ultimately, most people want to know their bike’s rough top speed. Yes, mods and other items impact a KX65 top speed potential, but at the end of the day, people just want to have an idea of how fast their bike is.

With that in mind, a KX65 top speed is about 45-50 mph.

Frequently Asked Questions About the KX65 top speed

How fast can a 65 dirt bike go?

There are a lot of factors that impact how fast a 65 dirt bike can go, but generally, they can go about 40-55 mph.

What age is a KX65 for?

A KX65 is usually for children between the ages of 7 and 10 years old.

How many gears does a KX65 have?

The newer KX65 has a six-speed manual transmission, meaning a KX65 has six gears.

What CC is a KX65?

A KX65 is technically 64cc, but Kawasaki rounds up to 65 in the model name “KX65.”

Is a KX65 a good bike?

Yes, a KX65 is a good bike. In fact, it’s one of the most dominant children’s motocross bikes.

Is a KX65 2 stroke?

Yes, the KX65 dirt bikes from Kawasaki have 2 stroke engines, not a 4 stroke engine.