Yamaha YZ 250 (2002-2004): A Two-Stroke Legend That Still Thrills

Introduction

The early 2000s marked a golden era for two-stroke motocross bikes, and the Yamaha YZ 250 (2002-2004) stands tall as one of the most iconic dirt bikes of its time. While modern four-strokes dominate today’s tracks, this generation of the YZ 250 remains a benchmark for raw power, lightweight agility, and bulletproof reliability. Whether you’re a vintage MX enthusiast or a rider looking for an affordable track weapon, this Yamaha demands respect. Let’s dissect why this two-stroke beast still puts grins on faces two decades later.

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Engine Performance: The Heart of a Rebel

At the core of the 2002-2004 YZ 250 lies a 249cc liquid-cooled two-stroke engine that’s equal parts brutal and refined. The 66.4 mm x 72.0 mm bore and stroke combination delivers explosive mid-range punch, while the 9.0:1 compression ratio (2004 model) ensures crisp throttle response. Yamaha’s patented Yamaha Power Valve System (YPVS) works seamlessly here, broadening the powerband so you’re not constantly chasing the "hit."

Twist the throttle, and the engine barks to life with that signature two-stroke braap. There’s no gentle introduction – the YZ 250 launches forward with a surge of torque that’ll have you wrestling the handlebars in the best way possible. Unlike some peaky competitors, this engine pulls hard from mid-range to top-end, making it forgiving for intermediate riders yet still thrilling for experts. On tight tracks, short-shifting works wonders, while open trails let you stretch its legs – though you’ll rarely need to tap into the 8,500 RPM ceiling.

The 5-speed transmission is slick and precise, though the close-ratio gearing means you’ll be working the clutch in technical sections. Speaking of which, the hydraulic clutch (a rarity in its class back then) offers buttery modulation, saving your forearms during marathon motos.

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Chassis and Handling: Lightweight Precision

Weighing just 97 kg (214 lbs) dry, the YZ 250 feels like a mountain bike with a rocket engine. The 1485 mm (58.5-inch) wheelbase strikes a perfect balance between stability at speed and flickable agility in corners. Yamaha’s semi-double cradle aluminum frame (introduced in 1999 and refined here) provides predictable flex, absorbing chatter while maintaining razor-sharp feedback.

Throw it into a rutted corner, and the YZ carves like it’s on rails. The 990 mm (39-inch) seat height might intimidate shorter riders, but the narrow chassis lets you grip the bike with your knees effortlessly. Standing up through whoops? The 391 mm (15.4-inch) ground clearance ensures you’re rarely dragging pegs or pipes.

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Suspension: Soaking Up the Chaos

Yamaha nailed the suspension setup for this generation. Up front, the 48mm KYB telescopic forks offer 300 mm (11.8 inches) of travel, adjustable for compression and rebound. Out back, the KYB Monocross shock delivers a plush 315 mm (12.4 inches) of rear wheel travel.

Stock settings are firm for aggressive track use but can be softened for trail riding. The forks handle hard landings with poise, resisting bottoming even on 10-foot drops. Meanwhile, the rear shock stays composed through braking bumps, though faster riders might want to stiffen the high-speed compression damping.

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Brakes and Wheels: Stopping Power Meets Durability

The single 245 mm (9.6-inch) front disc and rear disc provide ample stopping power for a 97 kg machine. Nissin calipers offer progressive bite – not as sharp as modern Brembos, but more than adequate when you’re charging into hairpins.

Tire sizes follow classic MX specs:
- Front: 80/100-21 (2002) or 80/90-21 (2004)
- Rear: 110/90-19

The 21-inch front wheel rolls over roots and rocks effortlessly, while the 19-inch rear hooks up predictably in loose dirt. Swap the stock tires for modern rubber like Dunlop MX33s, and you’ll unlock even more grip.

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Competition: How the YZ 250 Stacks Up

In the 2000s two-stroke arena, the YZ 250 faced fierce rivals:

1. Honda CR250R (2002-2004):
2. Engine: More top-end power but less low-end grunt
3. Handling: Heavier feel at 103 kg (227 lbs)

4. Verdict: YZ’s broader powerband and lighter chassis win for versatility

5. KTM 250 SX (2002-2004):

6. Engine: Sharper hit, harder to control
7. Suspension: WP components stiffer for pro riders

8. Verdict: YZ’s smoother delivery better suits mortals

9. Suzuki RM250 (2002-2004):

10. Handling: Razor-sharp turn-in rivals YZ
11. Engine: Weaker mid-range compared to Yamaha
12. Verdict: YZ strikes a better balance

The Yamaha’s standout feature? Reliability. While KTMs of this era needed frequent top-end rebuilds, the YZ’s engine could endure seasons of abuse with basic maintenance.

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Maintenance: Keeping the Beast Alive

Owning a 20-year-old motocross bike means staying vigilant with upkeep. Here’s your YZ 250 survival guide:

1. Engine Rebuilds:
2. Two-strokes eat pistons for breakfast. Replace rings every 30-40 hours and pistons every 60-80 hours.

3. Pro Tip: Upgrade to a forged piston (Wiseco or ProX) for longevity.

4. Air Filter Care:

5. Clean after every ride using biodegradable solvent.

6. Consider a Twin Air filter with pre-filter skin for dusty conditions.

7. Suspension Service:

8. Change fork oil every 50 hours.

9. Rebuild shock annually if ridden hard.

10. Brake Upgrades:

11. Swap pads to EBC MX-S series for better bite.

12. Replace braided stainless lines if lever feel gets spongy.

13. Cooling System:

14. Flush coolant annually. Use Engine Ice for better heat dissipation.

At MOTOPARTS.store, we stock everything from OEM gasket kits to performance reeds. Don’t forget a spark arrestor if you venture into forests!

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Conclusion: Timeless Adrenaline

The 2002-2004 Yamaha YZ 250 isn’t just a relic – it’s a testament to how good two-strokes can be. Its explosive power, telepathic handling, and rugged simplicity make it a favorite among riders who value skill over electronics. Whether you’re resurrecting a barn find or upgrading a well-loved example, this Yamaha rewards those who respect its wild nature.

Ready to unleash (or tame) the beast? MOTOPARTS.store has the gear to keep your YZ 250 screaming for another decade.

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Specifications sheet

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