Kawasaki KX 250 (2005-2008): A Two-Stroke Motocross Legend Revisited

Introduction

The Kawasaki KX 250 (2005-2008) represents the final golden era of factory two-stroke motocross bikes before four-stroke dominance took over. This generation of the KX 250 is a time capsule of raw power, lightweight agility, and the unmistakable scream of a carbureted two-stroke engine. Designed for riders who thrive on adrenaline and mechanical simplicity, this bike remains a cult favorite among motocross purists and vintage enthusiasts. Let’s dive into what makes this machine a standout, even when viewed through a modern lens.

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Design & Ergonomics: Built for Aggression

The KX 250’s design screams purpose. Cloaked in Kawasaki’s signature Lime Green with black accents (added in 2006), the bike looks fast even when stationary. The perimeter-style steel frame paired with an aluminum subframe strikes a balance between rigidity and weight savings, resulting in a dry weight of 97 kg (214 lbs)—a figure that still rivals modern four-strokes.

The riding position is aggressive, with a 965 mm (38-inch) seat height that positions the rider “in” the bike rather than “on” it. Narrow bodywork and a flat seat profile allow easy movement during hard cornering or mid-air adjustments. The handlebars are wide and grippy, though many riders upgrade to aftermarket options for personalized control. Ground clearance sits at 340 mm (13.4 inches), ensuring minimal hang-ups on rutted tracks or rocky trails.

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Engine Performance: Pure Two-Stroke Fury

At the heart of the KX 250 lies a 249cc liquid-cooled two-stroke engine with a Keihin PWK38S carburetor and Kawasaki’s Power Jet system. The result? Explosive mid-range punch and a relentless top-end rush that four-strokes struggle to replicate.

• Power Delivery: The engine’s character is unapologetically wild. Throttle response is instantaneous, and the 10.5:1 compression ratio ensures a broad powerband. Novices might find the hit abrupt, but seasoned riders will appreciate how the power builds linearly before erupting into a frenzy of acceleration.
• Gearbox: The 5-speed transmission is bulletproof, with precise shifts and a clutch that handles abuse. Gear ratios are optimized for motocross, though the bike can be re-sprocketed for off-road versatility.
• Sound & Smell: The raspy exhaust note and the sweet scent of premix fuel (50:1 ratio) are pure nostalgia. Modern fuel-injected bikes feel sterile in comparison.

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Handling & Suspension: Confidence on Rough Terrain

Kawasaki’s chassis and suspension setup on this generation KX 250 is a masterclass in balance. The 48mm inverted front fork offers 300 mm (11.8 inches) of travel, with 16-way compression and rebound damping adjustments. Even on choppy tracks, the front end stays planted, absorbing square-edged hits without deflection.

Out back, the UNI-TRAK® linkage system pairs with a fully adjustable shock providing 310 mm (12.2 inches) of rear wheel travel. The system excels at tracking through braking bumps and maintaining traction on exits.

Handling Highlights:
- Rake Angle: 26° steering geometry for quick turn-in without sacrificing stability.
- Wheels: Lightweight 21-inch front and 19-inch rear wheels wrapped in Dunlop tires (80/90-21 front, 110/90-19 rear) offer predictable grip.
- Brakes: Single discs front and rear (2005) upgraded to a front double disc in 2006–2008. While not as powerful as modern setups, they’re more than adequate for controlling two-stroke power.

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Competition: How the KX 250 Stacks Up

The 2005–2008 KX 250 faced fierce rivals in the two-stroke motocross segment:

1. Yamaha YZ250: The YZ250’s engine is slightly smoother, with a broader powerband. However, the KX 250’s suspension feels plusher on hard landings.
2. Honda CR250R: Honda’s chassis is sharper, but its case-reed engine lacks the KX’s explosive mid-range.
3. Suzuki RM250: The RM250 is lighter and turns quicker, but the KX 250’s reliability and parts availability give it an edge.

Against four-strokes like the Yamaha YZ250F or Honda CRF250R, the KX 250 trades tractable power and ease of riding for visceral excitement and lower maintenance costs.

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Maintenance: Keeping the Green Beast Alive

The KX 250’s simplicity is its greatest maintenance advantage. Here’s what owners should prioritize:

1. Premix Fuel: Always use high-quality 2-stroke oil at a 50:1 ratio. Modern synthetics like Motorex Cross Power 2T reduce carbon buildup.
2. Air Filter: Clean the foam filter after every ride. Consider a Twin Air filter with a pre-filter wrap for dusty conditions.
3. Suspension: Rebuild forks and shock annually. Upgrade to SKF seals for longevity.
4. Top-End Rebuilds: Pistons and rings should be replaced every 30–40 hours. Wiseco forged pistons are a popular upgrade.
5. Carburetor Tuning: Jet the PWK38S for your altitude. JD Jet Kits simplify fine-tuning.

MOTOPARTS.store Recommendations:
- Swap the stock chain for a DID ERT3 for durability.
- Install a Pro Circuit Platinum 2 pipe to amplify mid-range power.
- Replace brake pads with EBC MX-S series for improved bite.

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Legacy & Final Thoughts

The 2005–2008 Kawasaki KX 250 is a testament to an era when motocross was ruled by lightweight, high-revving two-strokes. Its combination of raw power, agile handling, and mechanical simplicity makes it a joy to ride—and a nightmare for competitors at the gate. While modern bikes have eclipsed it in refinement, few machines deliver the same primal connection between rider and machine.

For those lucky enough to own one, the KX 250 is a canvas for customization. Whether you’re chasing vintage trophies or just reliving the glory days, this Kawasaki remains a motocross icon that’s as thrilling today as it was two decades ago.

Upgrade your KX 250 with confidence using MOTOPARTS.store’s curated selection of aftermarket parts—because even legends deserve a little modern love.

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Specifications sheet

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