KTM 250 SX (1998–2002): A Two-Stroke Motocross Legend Revisited

Introduction

The late ’90s and early 2000s marked a golden era for two-stroke motocross bikes, and the KTM 250 SX stood tall as a fierce contender in the 250cc class. Built for riders who craved raw power, agility, and a no-nonsense approach to racing, this Austrian machine carved its reputation on tracks and trails worldwide. Even by today’s standards, the 1998–2002 generation of the KTM 250 SX remains a thrilling ride—a testament to KTM’s early commitment to performance-oriented engineering. Let’s dive into what makes this bike a timeless piece of motocross history.

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Design & Aesthetics: Orange Crush

KTM’s signature orange-and-silver livery has always been eye-catching, and the 250 SX wears it with pride. The 1998–2002 model features a slim, aggressive profile that screams speed even when stationary. The bodywork is minimalist, with sharp angles and a narrow waist designed to let riders grip the bike effortlessly with their knees.

The steel chassis, paired with a compact layout, keeps the weight centralized—a critical factor for maneuverability. At 101 kg (222.7 lbs) dry, it’s remarkably light, giving modern four-strokes a run for their money. The tall seat height (typical of motocross bikes) might intimidate shorter riders, but it provides ample room for shifting body weight during jumps or tight corners.

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Engine Performance: Two-Stroke Fury

The heart of the KTM 250 SX is its 249cc liquid-cooled two-stroke engine, a powerhouse that delivers explosive acceleration. Two-stroke purists will love the visceral hit of power as the revs climb. The engine’s character is unapologetically wild: it’s all about high-RPM bursts and a narrow powerband that demands precise throttle control.

• Low-end grunt: While two-strokes aren’t known for torque, the 250 SX manages decent pull off the line thanks to KTM’s tuned exhaust system.
• Mid-range punch: This is where the bike shines. The power valve opens up aggressively, launching you out of corners with a surge that feels like a nitrous boost.
• Top-end scream: Hold the throttle wide open, and the engine screams to its 9,500 RPM limit, ideal for clearing long jumps or straightaways.

The kickstarter is reliable but requires a firm boot—no electric start here, keeping the weight down and the experience authentically old-school. Riders will need to mix fuel at a 40:1 ratio (3.2 oz of oil per 1 US gallon), a small price to pay for the two-stroke’s simplicity and ease of maintenance.

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Handling & Suspension: Precision in the Dirt

The KTM 250 SX’s chassis is a masterclass in balance. The 1481 mm (58.3-inch) wheelbase offers stability at speed without sacrificing flickability in tight sections. Combined with the lightweight frame, the bike feels telepathic when carving ruts or navigating whoops.

Suspension setup:
- Front: The 48mm WP upside-down forks (a rarity in this era) soak up bumps with progressive damping. They’re stiff enough for hard landings but compliant over smaller irregularities.
- Rear: A WP monoshock with adjustable preload and rebound keeps the rear wheel planted, even when accelerating hard out of loose terrain.

Braking is handled by single discs front and rear. The front brake lacks the bite of modern systems but offers progressive feel—ideal for modulating speed in slippery conditions. The rear brake is sharp and responsive, perfect for scrubbing speed before corners.

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Competition: How Does It Stack Up?

In the late ’90s, the 250cc motocross segment was fiercely competitive. Let’s see how the KTM 250 SX fared against its rivals:

1. Yamaha YZ250 (1998–2002):
2. The YZ250 was smoother, with a broader powerband that forgave sloppy throttle inputs.

3. KTM countered with superior suspension (WP vs. Yamaha’s KYB) and a lighter chassis.

4. Honda CR250R (1998–2002):

5. Honda’s chassis was more rigid, favoring precision over comfort.

6. The CR250R had a stronger low-end but couldn’t match the KTM’s mid-range “hit.”

7. Suzuki RM250 (1998–2002):

8. Suzuki’s trademark was razor-sharp handling, but the RM250’s engine felt anemic compared to the KTM’s.

Verdict: The KTM 250 SX wasn’t the most polished bike in its class, but it offered a thrilling, race-ready experience straight off the showroom floor. Today, it’s a favorite among vintage motocross enthusiasts for its raw character and tunability.

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Maintenance: Keeping the Beast Alive

Owning a two-stroke like the KTM 250 SX requires diligence, but the payoff is a machine that’s simpler and cheaper to maintain than modern four-strokes. Here’s what to prioritize:

1. Engine Rebuilds:

2. Two-strokes eat pistons for breakfast. Replace the piston and rings every 30–40 hours of hard riding. Consider upgrading to a forged piston (available at MOTOPARTS.store) for durability.

3. Cooling System:

4. The liquid-cooled engine relies on a clean radiator. Flush coolant annually and inspect for leaks.

5. Air Filter Care:

6. Dust is a two-stroke’s nemesis. Clean the air filter after every ride and oil it lightly. Our store stocks high-flow filters for improved airflow.

7. Suspension Tuning:

8. Old WP forks may suffer from worn seals. Rebuild kits are affordable and easy to install.

9. Chain & Sprockets:

10. The O-ring chain lasts longer but adds drag. Swap to a lightweight non-O-ring chain for racing, and always adjust tension to 25–35 mm (1–1.4 inches).

Pro Tip: Keep a spare spark plug handy. Two-strokes are notorious for fouling plugs in slow, technical sections.

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Conclusion: Why the KTM 250 SX Still Matters

The 1998–2002 KTM 250 SX isn’t just a relic—it’s a living, breathing reminder of why two-strokes dominated motocross for decades. Its combination of brutal power, nimble handling, and minimalist design makes it a joy to ride, even in an era dominated by four-stroke technology.

For riders today, this bike offers a chance to experience unfiltered motocross adrenaline. And with MOTOPARTS.store’s extensive catalog of aftermarket parts, keeping it in peak condition is easier than ever. Whether you’re restoring a barn find or upgrading a well-loved racer, the KTM 250 SX deserves its spot in your garage.

Ride hard, ride smart, and let the two-stroke symphony play on.

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Specifications sheet

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