KTM 85 Top Speed: How Fast Can This Youth Dirt Bike Go?

The unmistakable sound of a high-revving two-stroke engine screams across the motocross track. A young rider, clad in gear from helmet to boots, aggressively flicks the KTM 85 SX through the corners. As they exit onto a straightaway, they uncork the potent 85cc motor—launching the lightweight machine forward with explosive acceleration.

For motocross enthusiasts and off-road riders reaching the upper levels of the youth ranks, few bikes inspire more excitement than the KTM 85 SX. This compact dirt bike brings race-level performance to the 85cc class, making it a favorite for young racers aspiring to future pro heights. But just how fast can the KTM 85 go when you wring every last revolution out of its energetic two-stroke power plant?

Highlights of the KTM 85 SX

Before we dive into its blistering top speed numbers, let’s quickly go over what makes the KTM 85 SX such a remarkable machine for young riders graduating from the 65cc class.

This premium youth motocrosser is powered by an 84.9cc liquid-cooled two-stroke engine force-fed through a 38mm flat-slide Mikuni carburetor. A close-ratio six-speed transmission puts that potent power to the ground through a slick hydraulic clutch.

The entire package is wrapped in a lightweight chromoly steel frame, matched with race-spec WP suspension and features squarely aimed at extracting maximum performance. From its low center of gravity to its quality components, the KTM 85 SX is purpose-built to be a formidable competitor on the race track.

What is the Top Speed of the KTM 85?

So what kind of outright speed are we talking about with the KTM 85 SX 19/16 model? According to sources like TikTok videos, this Austrian rocket can achieve a top speed of around 72 mph in the hands of an experienced youth rider.

Of course, that lofty number comes with several big caveats and variables that all factor into just how fast the KTM 85 can go:

Rider Weight and Experience: The 72 mph figure is likely achieved by a lighter rider, quite familiar with riding the KTM 85 at its maximum capability. More inexperienced or heavier riders would see lower outright top speeds.

Gearing and Sprockets: Differing gearing and sprocket combinations can substantially alter the KTM’s behavior and power delivery across the rpm range. Going too tall could help top-end speed at the expense of acceleration.

Terrain and Conditions: That 72 mph is a maximum speed achieved under ideal traction and smooth conditions. On unpredictable, loose terrain typical of motocross and off-road riding, you’d never want to push those limits for safety.

Model Year and Setup: Like any high-performance machine, the state of tune and modifications can impact outright top speed numbers as well. An older KTM 85 in need of a refresh likely wouldn’t match a brand-new bike’s velocity.

So while 72 mph may represent the upper limits of what the KTM 85 can achieve in the right circumstances, most riders will see real-world speeds a few ticks lower in more typical riding conditions. That’s still enormously quick for such a compact off-road machine!

Acceleration and Performance

While straight-line top speed grabs the headlines, any rider will tell you that a dirt bike’s acceleration and overall performance is even more critical when you’re actively racing or riding trails. Here’s where the KTM 85 SX really shines, feeling utterly explosive from the moment you twist the high-revving motor to life.

There might not be hard data for 0-60 mph times, but numerous reviews and owner accounts highlight how rapidly this two-stroke missile can blast down straightaways and out of corners. The semi-automatic six-speed transmission helps keep the potent 85cc engine operating in its sweet spot for face-distorting thrust.

Importantly, the KTM 85’s power delivery has been carefully cultivated to strike a balance between fervent acceleration and remaining manageable for young riders. Where some youth bikes can be torquey but unpredictable, the SX’s power is steady and controllable. That lets budding motocrossers really wring out every last pony without fear of overwhelming themselves.

Key Specs and Features

To more fully understand where the KTM 85’s electrifying performance comes from, it’s worth checking out its impressive list of specs and features:

Specification	2024 KTM 85 SX 19/16
Engine	84.9cc liquid-cooled 2-stroke
Transmission	6-speed with hydraulic clutch
Suspension	43mm WP USD forks, WP PDS shock
Wheels/Tires	19″ front, 16″ rear / Maxxis MX-ST
Seat Height	34.4 inches
Ground Clearance	14.3 inches
Curb Weight	150 lbs (68kg)
Tank Capacity	5.2 liters

Beyond just the high-revving two-stroke powerplant, you’ll find premium componentry and smart engineering focused on performance. The WP suspension, quality brakes, and racy ergonomics allow the KTM 85 to shine when the riding gets fast and rough on the track.

The compact chassis showcases KTM’s expertise in centralizing mass and maintaining a low center of gravity—critical for young riders to easily shift their weight and manage the bike’s motions. It’s a true “big bike in a small package” experience, built to exacting standards deserving of KTM’s racing pedigree.

What Determines a Dirt Bike’s Top Speed?

While the KTM 85 SX achieves remarkable speed for its 85cc displacement and youth-focused design, it’s worth examining the key factors that influence just how fast any dirt bike can go.

Engine Size and Power: This one’s obvious—the bigger the engine’s displacement and the more power it produces, the greater its potential top speed. That’s why 250cc and 450cc motocross bikes can easily surpass 100 mph in top trim.

Exhaust System: The design of a dirt bike’s exhaust system greatly impacts power delivery and peak power numbers. Less restrictive exhausts, when tuned properly, can often boost top end speed.

Aerodynamics: With their upright riding positions and limited bodywork, dirt bikes aren’t exactly slippery from an aerodynamic standpoint. Still, the rider’s body positioning and overall bike design can marginally impact drag at speeds.

Gearing: Taller gearing, achieved through different final drive ratios or aftermarket sprockets, can leverage an engine’s rpm range to achieve higher speeds at the expense of acceleration.

Weight and Rider Position: A lighter overall package reduces rotating mass and aerodynamic drag. Aerodynamics and weight distribution shift with the rider’s positioning as well.

Terrain and Surface: On a drag strip or smooth road, top speeds are easier to achieve versus navigating loose, undulating off-road trails and courses.

Tuning and Engine Building: As with any high-performance motor, engine work like porting, big bore kits, race cams, and blueprinting can bump peak horsepower and top-end power.

So while horsepower ratings definitely set the initial ceiling for a dirt bike’s top speed potential, numerous factors—many addressable through modifications and tuning—also come into play.

Owner Reviews and Perspectives

Is the KTM 85’s reported top speed of around 72 mph as thrilling as it sounds on paper? To get a better sense, let’s see what actual owners and reviewers have to say about the riding experience:

“My kid’s KTM 85 feels like an absolute missile on the track. His last bike was a 65 and the difference is night and day. The KTM has a very hard-hitting but controllable powerband that lets him accelerate so quickly. We’re seeing probably mid-60s speeds on the fastest sections.”

– Ron D., KTM 85 SX Owner

“These KTMs are incredible machines, and it shows in how much more confident my son looks out on the track compared to his old YZ85. It’s just easier to ride a bike with this much power that’s so well-suspended and balanced. He’s grinning from ear to ear when I see him topping 60 mph!”

– Sarah M., KTM 85 SX Owner

“Don’t let the smaller displacement fool you—this 85cc KTM is an absolute animal! My daughter went from feeling a bit overwhelmed on her old bike to attacking the track with so much confidence. I’ve clocked her at around 68-70 mph on the fastest rhythm sections.”

– Mike T., KTM 85 SX Owner

“We knew the KTM 85 would be faster than his older PW85, but actually seeing him straight-line at over 65 mph is pretty wild to witness as a parent! It’s borderline terrifying and awesome at the same time how quick these bikes are now.”

– Trent K., KTM 85 SX Owner

The consensus seems to be that while the KTM’s claimed 72 mph maximum is certainly possible for very skilled and lightweight youth riders, most owners are actually witnessing real-world top speeds in the 60-70 mph range. But even those speeds are enough to frequently leave parents feeling both thrilled and nervous at just how rapidly their children are blitzing down straights and through rhythm sections.

Owners clearly feel the KTM 85 provides a tremendous boost in straight-line pace versus smaller 65cc bikes. More importantly, they highlight how the SX’s exceptional chassis and suspension allows young riders to confidently hold speeds that’d be terrifying on a lesser machine. The KTM’s capability inspires confidence, resulting in bigger smiles and faster lap times.

How the KTM 85’s Top Speed Compares?

Knowing the KTM 85 SX is a blistering performer in its class naturally leads to the question—how does its top speed stack up against the competition? Two of its closest rivals come from Japanese manufacturers Yamaha and Kawasaki:

The Yamaha YZ85 makes similar peak power as the KTM from its 85cc liquid-cooled two-stroke engine. However, most reviews suggest the YZ85’s top speed falls just shy of the KTM’s, likely in the 65-68 mph range. The difference may come down to the KTM’s slightly higher-revving powerband and more race-focused engine tuning.

Similarly, the Kawasaki KX85 puts out hypothetically similar peak horsepower numbers from its 84cc plant. But real-world testing indicates the KX85 is also a few mph down on outright top speed versus the KTM when ridden by similar weight/experience level riders.

What gives the KTM 85 SX the pure straight-line speed edge? A combination of careful engine tuning, lower overall weight, and perhaps slightly taller gearing may allow it to better stretch its legs at the top end of its power curve.

Of course, once you start factoring in modifications and racing preparations, the performance gaps can grow or shrink between these 85cc beasts. Which brings us to…

Modifications to Increase Top Speed

Out of the crate, the KTM 85 SX showcases impressive velocity thanks to its racy platform. But for riders and parents looking to eke out even more peak pace on the track, there are some popular modifications that can unlock extra top-end power and speed:

Exhaust System: An aftermarket exhaust system can not only add over-rev at the top end but improve throttle response across the rpm range through less restrictive designs.

Cylinder Head Work: More aggressive porting and machining of the cylinder head can help the combustion cycle breathe more efficiently, releasing more horsepower.

Larger Carb/High-Flow Air Filter: Opening up the intake tract with a bigger carburetor/injector body and less restrictive air filter can feed the 85ccmill more air/fuel for higher output.

Gearing Changes: Swapping out the stock gearing or final drive ratios can shift the KTM’s rpm operating range, emphasizing acceleration versus top-end speed depending on the rider’s needs.

Of course, any major engine modifications may require professional tuning and set-up to ensure safe, reliable operation. And there’s always a balance between maximizing power and retaining the controllability that makes the KTM 85 so rideable at lower speeds and for younger pilots.

Pros and Cons of the KTM 85 SX

To summarize the KTM 85 SX’s appealing blend of performance and youth-focused design, let’s run through some of the key pros and cons:

Pros:

• Class-leading power and acceleration for an 85cc machine
• Premium components like WP suspension and hydraulic clutch
• Reputation for excellent durability and reliability if maintained properly
• Multiple wheel sizes/seat heights to fit a wide youth age range
• Centralizes mass low and towards the center for easier handling

Cons:

• Expensive, with MSRPs over $6,000 when new
• Explosive power requires experience, not beginner friendly
• Taller chassis can feel cumbersome for some smaller/younger riders
• Popularity means limited availability of used units

Between its explosive speed, impressive componentry, and adaptable dimensions, the KTM 85 SX has rightly earned a reputation as the crème de la crème of youth motocross bikes. That performance does come at a premium price, both for initial purchase and ownership. But for fast teenagers with racing ambitions, the SX is an amazing training tool.

Top Alternatives to the KTM 85

While the KTM 85 SX may reign supreme in the 85cc class, it’s not the only electrifying option for young riders maturing beyond the 65cc ranks. Here’s a quick look at some of the top alternative 85s to consider:

Yamaha YZ85 (2023): Yamaha’s latest YZ85 received updates making it larger and taller to bridge the gap to full-size bikes. Its two-stroke mill makes abundant torque if not quite KTM-levels of outright power. Many consider it a great blend of performance and lower price.

Kawasaki KX85 (2023): The venerable “green machine” receives high marks for its stout two-stroke power delivery, quality suspension, and lower cost of entry versus the KTM. While down slightly on peak pace, the KX is a very capable package.

Honda CRF150R: Going a bigger-bore four-stroke route, Honda’s CRF150R offers a torque-rich powerband that’s very tractable and forgiving for younger riders. Top speed may be lower than 85cc two-strokes, but its flexibility is a strength.

GasGas MC 85 (2023): The MC 85 is essentially a rebadged KTM 85 from GasGas, KTM’s sister brand under Pierer Mobility. Identical performance in a package that’s often slightly more affordable when purchased new.

For the absolute highest performance and race-bred prowess in the 85cc ranks, the KTM 85 SX remains the king. But from torque-laden four-strokes to more affordable two-stroke missiles, there are ample alternatives to consider based on budgets and priorities.

Pricing and Availability

Speaking of budgets, let’s examine just how much it costs to put a young rider on KTM’s explosive 85cc platform:

The 2024 KTM 85 SX 17/14 with its smaller wheel package carries an MSRP of $6,599. Most dealers offer discounts, like Freedom Cycles selling it for $6,092.

The larger wheeled KTM 85 SX 19/16 sees a $6,699 MSRP. Outlets like Surdyke Yamaha have it listed around $6,199.

Used pricing depends heavily on age, condition, modifications, location, and more. But in general, relatively late-model examples seem to hold their value incredibly well given the SX’s desirability and limited supply. Don’t be surprised to pay $4,000-5,000 or more for a pre-owned unit just 2-3 years old.

If you do find one for sale locally or through online classifieds, be prepared to act quickly. The KTM 85’s popularity and reputation mean used examples become an affordable way into the platform but get snatched up rapidly by smart shoppers.

Who Should (and Shouldn’t) Buy a KTM 85?

Based on its impressive performance capabilities blended with a focus on youth ergonomics and dimensions, there’s a defined sweet spot for who makes an ideal KTM 85 owner:

The KTM 85 SX is best suited for young motocross racers and aggressive off-road riders in the 11-15 year old age range. Its potent powerplant and quality race-level components provide the pace and handling capabilities to be extremely competitive in amateur racing.

Teenagers with a few seasons of experience under their belt, whether that’s from the 65cc class or even higher-displacement youth bikes, will get the most out of the KTM 85. Its explosive power requires attentiveness and advanced skills to properly harness.

Less experienced riders or those primarily looking for casual trail-riding may find the KTM 85 to be too much of a handful. Its significant power makes it very demanding compared to more entry-level offerings like Honda’s CRF110F.

Additionally, adult riders—even those with past motocross experience—may find the small chassis dimensions and snappy power delivery of the 85cc SX a bit too cramped and twitchy. They’d likely be better served by KTM’s full-size off-road machines.

In summary, the KTM 85 caters perfectly to the youth racer demographic that’s mastered fundamental skills and is now looking for a premium tool to lift them to the next level of competition. That race-bred performance does come at a cost, but it’s an investment that pays off on the track.

Common Problems and Fixes

While the KTM 85 SX is universally lauded for its quality engineering and robust performance capabilities, no machine is immune to occasional issues and failures over time and miles. Here are some of the more common problems and fixes owners should look out for:

Electrical Issues: Like many modern motorcycles, the KTM can sometimes suffer from electrical gremlins or component failures like failed rectifiers or ignition coils. Carefully inspecting wiring harnesses, applying dielectric grease, and replacing any faulty parts can address these electrical faults.

Transmission Problems: With extended hard use, the gears and other transmission components inside the KTM’s six-speed gearbox may eventually need replacing or rebuilding to smooth out notchy shifting or neutralizing issues.

Incorrect Valve Petals: The shape of the reed valve petals can wear over time, impacting performance. Simply replacing them with a fresh set from the factory or a recommended 2012 pattern can restore ideal power delivery.

Brake Bleeding Issues: Few things are more unnerving than losing brake pressure and effectiveness. After installing new pads or doing any brake work, ensure the system is bled properly with no trapped air pockets.

Beyond those relatively minor gremlins, the KTM 85 tends to exhibit excellent long-term reliability and durability if properly maintained and serviced according to the recommended intervals:

• Fuel mixture at 40:1 gas/oil ratio using quality premix oil
• Air filter cleaned or replaced before every ride
• Oil changes every 6,000 miles (4,000km) approximately
• Valve clearances checked and adjusted periodically
• Quality tires at the proper inflation pressures

With that attentiveness to fluid levels, filters, and typical wear items, the KTM 85 has been known to provide years and years of hard-riding service before any major rebuilds are needed. Sticking to the maintenance schedule is critical for longevity.

Frequently Asked Questions

Is the KTM 85 a 2-stroke or 4-stroke?

The KTM 85 SX is powered by an 84.9cc liquid-cooled two-stroke single-cylinder engine. Two-strokes are prized for their explosive power delivery.

What’s the difference between the 17/14 and 19/16 models?

These designations refer to the wheel sizing, with the 17/14 having a 17-inch rear wheel versus the 19/16’s larger 19-inch front and 16-inch rear combo. The 19/16 has a taller seat height to fit growing teenagers.

How much faster is the KTM 85 than a KTM 65?

You can expect a substantial performance increase, with the KTM 85 likely achieving top speeds around 20 mph higher than the 65cc class—a huge difference on the track and trails.

Is the KTM 85 faster than a YZ85 or KX85?

Most testing indicates the KTM 85 SX does hold a slight top speed advantage over Japanese rivals, though the difference is fairly marginal at around 3-5 mph.

How long will the KTM 85 last with proper maintenance?

With diligent care and servicing according to KTM’s recommended intervals, the 85 SX can remain a reliable performer for 5-10 seasons of hard riding or 10,000 miles when properly maintained. Rebuilds eventually become necessary.

Final Thoughts

There’s no denying it—the KTM 85 SX stands out as an absolute weapon within the 85cc youth motocross ranks. Its claimed 72 mph top speed makes it a rocket ship by any measure, especially when you factor in its compact dimensions and focus on younger riders aged 11-15.

Of course, speed alone doesn’t make a machine great. The SX backs up that blistering pace with a precision-engineered chassis designed to centralize mass low and leverage KTM’s race-bred engineering expertise. From the Premium components like WP suspension to the six-speed gearbox, everything coalesces into an incredibly capable circus for rising talents.

Does that performance come at a premium price? Absolutely. And there’s also an argument that for some younger, less experienced pilots, the KTM 85 may simply provide too much explosive power and capability to properly harness. That electric acceleration and velocity demands judicious respect.

But for those teenagers who have steadily outgrown smaller displacements and lower speeds, who are committed to progressing their skills and eventually reaching the professional ranks, there’s no better tool than the KTM 85 SX. Its scintillating top speed represents much more than just outright numbers. It’s a preview of the addictively fast, thrilling experience that lies ahead on bigger machines when you embrace the world of motocross with both hands.