1997 Yamaha YZM400F

Doug Henry's history-making MXer

1997 Yamaha YZM400F

In the mid-1990s, two-stroke motorcycles weren’t just considered the best option for Supercross, where light weight and explosive power were critical. They were the only option.

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But then came Yamaha, which fired the first shot in what would become the modern four-stroke MX revolution with this YZM400F—a full-factory prototype with Doug Henry at the controls. Ultimately, it proved that valves and cams could not only compete with reed cages and pre-mix on a Supercross track, they could beat them.

The bike was more than just a different motor, though. To encourage development of new race-proven technology, in 1997 the AMA started offering manufacturers a one-year exemption from a long-time rule that required teams to start with production motorcycles when building their race bikes.

Yamaha took advantage and rolled out this bike.

The YZM400F featured a hand-built main frame; a carbon-fiber subframe, airbox and engine mounts; magnesium clutch and flywheel housings; a hand-built aluminum gas tank; and a titanium exhaust.

In its first race, at the AMA Motocross opener in Gainesville, Florida, Henry rode the YZM to eighth overall, following that with a fourth and a sixth in the next two rounds.

But the YZM400F’s biggest race, and one of the most memorable of Henry’s career, came the following weekend at the Las Vegas finale of the 1997 AMA Supercross Championship. Henry, who raced a YZ250 two-stroke in the early Supercross rounds before he was temporarily sidelined by a minor injury, fielded the now-familiar YZM400F and won, showing the world that a four-stroke could beat two-strokes on their own turf.

Within a few years, four-strokes, not two, dominated professional motocross and Supercross competition, and it all started with Henry and the YZM.

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