Gas Gas SM 250 (2002-2004) Review: A Two-Stroke Supermoto That Defies Convention

Introduction

The Gas Gas SM 250 represents a fascinating chapter in supermoto history. Produced from 2002 to 2004, this Spanish-built machine dared to combine the raw, unfiltered energy of a two-stroke engine with the street-focused agility of a supermoto. While most manufacturers shifted toward four-stroke dominance in the 2000s, Gas Gas doubled down on its dirt bike heritage to create a lightweight, high-revving street weapon. Even today, this bike stands out as a rare breed—a snarling two-stroke supermoto that demands respect and skill from its rider. Let’s dissect what makes this machine tick and why it still turns heads decades later.

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Design & Chassis: A Purpose-Built Hooligan Machine

Frame & Ergonomics

The SM 250’s Deltabox frame—constructed from chromium-molybdenum steel tubing—is a masterpiece of minimalist engineering. Paired with an aluminum swingarm, it creates a rigid yet forgiving platform that shines in aggressive cornering. At 101 kg (222.7 lbs) dry, the bike feels almost unnervingly light when you first throw a leg over the 940 mm (37-inch) seat. Taller riders will appreciate the spacious cockpit, though the seat’s narrow profile and firm padding remind you this is no touring machine.

The red/grey/black color scheme—a signature of early-2000s Gas Gas models—gives the bike a no-nonsense, competition-ready aesthetic. Every design element serves a function, from the compact fuel tank (9.5L / 2.5 gal) to the high-mounted front fender that clears debris during impromptu off-road excursions.

Suspension Setup

Gas Gas didn’t cut corners here. The 50mm Marzocchi inverted forks offer 295 mm (11.6 in) of travel—substantial for a supermoto—while the Öhlins rear shock (320 mm / 12.6 in travel) delivers progressive damping perfect for absorbing urban potholes or track-day curbs. The setup leans slightly stiff for casual riders but rewards aggressive inputs with laser-precise feedback.

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Engine Performance: Two-Stroke Fury Meets Street Smarts

The Heart of the Beast

At its core lies a 249.3cc liquid-cooled two-stroke single—a configuration that’s nearly extinct in modern street bikes. With 49.8 HP @ 8,699 RPM and 45.4 Nm (33.5 lb-ft) @ 7,628 RPM, this engine doesn’t so much accelerate as it erupts. The powerband is classic two-stroke: docile below 6,000 RPM, then a violent surge that pins your elbows back until the 11,500 RPM limiter intervenes.

The 38mm Keihin PWK carburetor requires patience to tune (more on that later) but rewards with crisp throttle response. Unlike modern fuel-injected bikes, there’s an art to keeping this engine in its sweet spot—a skill that becomes second nature after a few rides.

Transmission & Clutch

The 6-speed gearbox is a revelation. Ratios are tightly stacked, letting you exploit every ounce of that narrow powerband. Shifts are positive but notchy compared to Japanese rivals. The hydraulic clutch lightens pull effort, though engagement is abrupt—a trait that makes slow-speed maneuvers challenging for novices.

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Riding Experience: Urban Guerrilla Warfare on Two Wheels

City Slicing

In urban environments, the SM 250 transforms traffic into a playground. The 340 mm (13.4 in) ground clearance lets you mount curbs effortlessly, while the 1475 mm (58.1 in) wheelbase ensures flickable agility. Filtering through gridlock feels like threading a needle—the bike’s narrow profile and instant steering response inspire confidence. Just remember: that two-stroke hit can turn a harmless lane change into a wheelie show if you’re heavy-handed.

Backroad & Track Manners

Find an open road, and the SM 250 reveals its split personality. The 120/60-17 front and 150/60-17 rear tires (a wide footprint for its era) offer tenacious grip, while the suspension soaks up mid-corner bumps without unsettling the chassis. Braking is handled by single 260mm front and 220mm rear discs—adequate for the bike’s weight but requiring a firm squeeze when scrubbing speed from triple-digit kph (60+ mph) bursts.

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Competition: How the SM 250 Stacks Up

Aprilia SX 50 / 125

Aprilia’s smaller-displacement two-strokes targeted a different demographic but shared the SM 250’s lightweight ethos. The SM 250’s larger engine and premium suspension components gave it a decisive edge in power and adjustability, though Aprilia’s build quality was arguably more refined.

Husqvarna SM 125/250

Husky’s four-stroke SM 250 (introduced later) offered easier maintenance and broader torque, but couldn’t match the Gas Gas’ power-to-weight ratio. The SM 250’s Öhlins rear shock also outclassed Husqvarna’s Sachs units in damping control.

KTM 625 SMC

KTM’s LC4-powered beast dwarfed the SM 250 in displacement and top-speed capability. However, the Gas Gas’ 50kg (110 lb) weight advantage made it far more playful in tight corners and urban environments.

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Maintenance: Keeping the Two-Stroke Flame Alive

Engine Care

• Oil Mixing: The 2.5% premix requirement (1:40 ratio) is non-negotiable. Use high-quality synthetic oils like Motul 710 to avoid carbon buildup.
• Piston Replacements: Plan for a top-end rebuild every 50-70 hours of hard riding. Stock pistons work, but aftermarket kits from Wössner offer improved durability.
• Carb Tuning: The Keihin PWK thrives with regular cleaning. Jet changes are inevitable if you’re riding at varying elevations.

Suspension & Brakes

• Fork Service: Replace Marzocchi fork oil every 100 hours. Consider upgrading springs for riders over 80kg (176 lbs).
• Öhlins Shock: Rebuilds are pricey but crucial every 200 hours. MOTOPARTS.store stocks seal kits and nitrogen recharge tools.
• Brake Pads: Organic pads work for street use, but sintered alternatives (like EBC FA416) enhance bite during aggressive riding.

Chain & Sprockets

The stock 520 chain wears quickly under two-stroke abuse. Upgrade to a DID ERV3 chain and steel sprockets for longevity.

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Final Thoughts: A Cult Classic Reimagined

The Gas Gas SM 250 isn’t for everyone—it’s a bike that demands engagement, rewards skill, and punishes complacency. Yet for those willing to master its two-stroke temperament, few machines deliver such visceral thrills per dollar (or euro). In an age of rider aids and homogenized performance, this Spanish rebel reminds us that motorcycling’s soul lies in raw, unapologetic mechanics.

Whether you’re hunting replacement parts for your own SM 250 or simply curious about two-stroke legends, MOTOPARTS.store has the expertise and inventory to keep your ride alive. From Öhlins rebuild kits to period-correct decals, we’re here to fuel your supermoto addiction.

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Specifications sheet

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