KTM 250 SX (2011-2016): A Two-Stroke Motocross Legend Revisited

For motocross riders who crave the raw, unfiltered adrenaline of a two-stroke engine paired with modern chassis dynamics, the KTM 250 SX (2011-2016) remains a benchmark. This generation solidified KTM’s reputation as a leader in competitive off-road machinery, blending Austrian engineering precision with the visceral thrill that only a high-revving 250cc two-stroke can deliver. After spending a day throwing this machine around a motocross track and technical trails, here’s why it still commands respect—and how it holds up against its rivals.

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Engine Performance: The Heart of a Predator

At the core of the KTM 250 SX lies its 249cc liquid-cooled single-cylinder two-stroke engine. With a bore and stroke of 66.4 x 72.0 mm (2.6 x 2.8 inches), this powerplant is all about explosive delivery. The reed-valve induction system and Keihin PWK carburetor (36mm or 38mm depending on the year) work in harmony to create a hit of power that’s both thrilling and demanding.

What It Feels Like to Ride:
Twist the throttle, and the engine responds with a sharp, almost electric surge. The powerband is classic two-stroke: tame at low RPMs, but once the revs climb past the midrange, the bike lunges forward with a frenetic intensity. On hard-packed tracks, this translates to effortless jumps out of corners. In deep ruts or sandy sections, it demands precise clutch control to keep the revs in the sweet spot.

The hydraulic clutch (Brembo on later models) is a standout feature. It’s featherlight—even after hours of abuse—and engages smoothly, making it easier to modulate power during technical climbs or tight turns. The 5-speed gearbox shifts cleanly, though the ratios feel closely spaced, requiring frequent shifts to stay in the meat of the power.

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Chassis and Handling: Precision Meets Agility

KTM’s chrome-molybdenum steel central-tube frame underwent subtle refinements during this generation, but the core philosophy stayed consistent: stiffness for stability, flex for compliance. Paired with WP Suspension components, the 250 SX feels like a scalpel on the track.

Front Suspension:
The 48mm WP USD forks (closed-cartridge on 2016 models) offer 300mm (11.8 inches) of travel. They’re stiff enough to handle big landings but sensitive to smaller bumps, giving a planted feel in choppy sections. Adjusting compression and rebound is straightforward, and most riders will find a sweet spot between aggression and comfort.

Rear Suspension:
The WP shock absorber (with Progressive Damping System on earlier models) delivers 185–335mm (7.3–13.2 inches) of travel depending on the year. It’s progressive enough to prevent bottoming-out during hard hits, yet supple when navigating rock gardens or root-infested trails.

Weight Distribution:
With a dry weight hovering around 95–97kg (209–214 lbs) and a wheelbase of 1,495mm (58.9 inches), the 250 SX feels flickable. Throwing it into berms or adjusting mid-air is intuitive, thanks to its centralized mass. The seat height—992mm (39.1 inches)—is tall but manageable for riders over 175cm (5’9”).

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Brakes and Tires: Confidence in the Rough

KTM equipped this generation with Brembo components: a 220–260mm front disc gripped by a four-piston caliper and a single-piston rear setup. The bite is aggressive but predictable—ideal for late braking before corners.

The stock tires (80/100-21 front, 110/90-19 rear) provide decent grip on intermediate terrain, but serious riders will swap them for softer compounds in mud or hard-pack-specific treads.

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Competition: How It Stacks Up Against the Rivals

The 250cc two-stroke motocross segment is niche but fiercely competitive. Here’s how the KTM 250 SX compares:

1. Yamaha YZ250

• Engine: Yamaha’s air-cooled 249cc two-stroke lacks the KTM’s liquid cooling, leading to power fade during long motos.
• Suspension: KYB forks are plush but less adjustable than WP’s offerings.
• Weight: At 103kg (227 lbs), the YZ250 feels heavier in technical sections.
• Verdict: The YZ250 is bulletproof but dated. The KTM wins on modern features and agility.

2. Husqvarna TC250 (Pre-Husky/KTM Merger)

• Engine: Similar power output but with a smoother delivery, suited to less aggressive riders.
• Chassis: Steel frame comparable to KTM’s but with a slightly plusher ride.
• Ergonomics: Husky’s flatter seat profile appeals to taller riders.
• Verdict: A close match, but the KTM’s hydraulic clutch and parts support give it an edge.

3. Suzuki RM250

• Legacy: Discontinued after 2008, but still popular used. Lacks the KTM’s refinements.
• Power: Softer low-end hit, requiring more clutch work.
• Verdict: The KTM dominates in modernity and race-ready specs.

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Maintenance: Keeping the Beast Alive

Owning a high-strung two-stroke like the 250 SX requires diligence. Here’s how to keep it in peak condition—and where MOTOPARTS.store can help:

1. Engine Care

• Piston Replacements: Two-strokes eat pistons. Replace every 30–40 hours for aggressive riders. Stock up on aftermarket piston kits.
• Carburetor Tuning: Clean the Keihin PWK every 20 hours. Consider a JD Jet Kit for altitude adjustments.
• Cooling System: Use high-quality coolant and inspect hoses regularly.

2. Suspension Service

• WP forks need oil changes every 50 hours. Upgrade to SKF seals for longevity.

3. Brake Upgrades

• Swap stock brake pads for sintered metal compounds in muddy conditions.

4. Chain and Sprockets

• The 520 X-ring chain lasts longer with proper tensioning. Pair it with anodized sprockets for reduced wear.

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Final Verdict: Why the 250 SX Still Matters

The KTM 250 SX (2011–2016) isn’t just a relic of the two-stroke era—it’s a testament to how visceral and engaging motocross can be. Its combination of razor-sharp handling, brutal power delivery, and race-ready components makes it a favorite for riders who value skill and excitement over four-stroke tractability. While newer bikes have eclipsed it in technology, few match its raw character.

Whether you’re resurrecting a barn find or fine-tuning a seasoned racer, MOTOPARTS.store has the upgrades and OEM replacements to keep your 250 SX biting at the competition’s heels.

Rev hard, ride harder.

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Specifications sheet

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