This Week in MXA, presented by O’Neal, Josh Mosiman is breaking in our 70th anniversary white and red 2026 Yamaha YZ250 two-stroke. This engine was fully built by Pro Circuit, identical to Ken Roczen’s 2022 Red Bull Straight Rhythm-winning YZ250 and Ryan Villopoto’s Two-Stroke World Championship bike from 2024. Surprisingly, with Pro Circuit’s head and cylinder mods, the Wiseco piston, the Pro Circuit billet clutch cover, all the gaskets, and labor, the engine price comes out to only $1500. However, we forgot to factor in the MotoTassinari V-Force4X reed valve ($165), the Pro Circuit Champ Stamp pipe ($384.95), and the R-304 silencer ($206.29. Also, on a separate bill, the revalved KYB suspension from Pro Circuit goes for just under $900.
The Yamaha YZ250 is one of the most legendary, iconic, and enduring dirt bikes in motocross history. First introduced in 1974, it holds the record for the longest-running production motocross model in the world. It is highly celebrated for its extreme reliability, competitive performance, and the raw, mechanical fun of a 250cc two-stroke engine.
🛠️ Key Technical Specifications
🚀 Engine Character & Performance
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The Two-Stroke Punch: Producing roughly 47 to 49 horsepower in stock form, the YZ250 delivers instant, hard-hitting power. It utilizes Yamaha’s patented Power Valve System (YPVS) to broaden the powerband, combining crisp bottom-end torque with a ferocious mid-range pull and singing top-end over-rev.
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Pure Simplicity: Unlike modern four-stroke engines with complex overhead cams, valves, and electronic fuel injection systems, the YZ250 uses a beautifully simple carbureted design. This makes it incredibly affordable and easy to rebuild for backyard mechanics.
🏁 Suspension & Handling Gold Standard
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KYB SSS Suspension: The YZ250’s absolute crown jewel is its KYB Speed-Sensitive System coil-spring fork. Decades after its introduction, it still sets the industry benchmark for production off-road suspension, offering an incredibly plush feel that resists harsh bottoming on massive jumps.
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Agile Aluminum Chassis: With a nimble, rigid aluminum frame and low overall weight, the YZ250 handles with exceptional sharpness. It transitions rapidly through tight corners and is notoriously fun and predictable in the air.
🌎 The Enduro & Freestyle Legend
Because of its incredibly versatile power delivery and indestructible build quality, the YZ250 isn’t just a motocross track weapon. It is highly sought after across multiple disciplines:
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Off-Road/Enduro: Easily converted into a woods-racing machine (often modified with a heavier flywheel weight and an rear wheel).
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Freestyle Motocross (FMX): For years, the YZ250 has been a premier weapon of choice for freestyle athletes globally due to its ultra-light chassis weight and crisp throttle response.
