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 National Motocross opener in Gainesville, Fla., Henry rode the YZM to eighth overall, following that with a fourth and a ...

This was the first Yamaha factory motocross machine with a 4-stroke engine. It was developed in an attempt to provide the same level of lightness and performance as a 250cc 2-stroke machine, said to be the fastest motocrosser at the time.

2017年1月1日 · Twenty years ago this month Yamaha dropped its game-changing four-stroke MXer bombshell, the YZM400F. The prototype set the precedent for a bold new era of four-stroke machinery. Aboard the prototype Doug Henry won the final Supercross round of …

2015年1月8日 · The YZM 400 is the real deal: a 1997 Yamaha works engine. It's the engine that changed history, and you could say the engine that killed the two-stroke. The engine is single-cylinder, four-speed, 5...

With its development of the YZM400F factory machine and YZ400F production motocrosser, Yamaha overturned the long-held belief of the industry (and the sport of Supercross) about 4-stroke motocrosser capability and competitiveness.

For the moment, it is a liquid-cooled, double-overhead-earn 400 in a frame that mimics YZ250 geometry. The engine’s centercases are CNC-machined out of billet. Basically, the machinists started with an enormous block of aluminum and cut away everything that didn’t look like a …

The development aim for the factory-spec YZM400F was performance potential on par with the 2-stroke YZ250 but in an even lighter package. To achieve this goal, Yamaha applied its technology and expertise garnered in motorcycle engine development and automobile racing (#2) in the 1980s and 1990s and began development of a unique DOHC 5-valve ...

One of Doug’s many claims to fame, is being the first racer of the new production YZ400F. I extracted this article from Pulpmx.com. Put best by Dan Lamb about how historically significant this engine is and how rare it is for years to come. There never will a be anything like it ever again.

2010年10月27日 · "Henry would race the production version of the prototype four-stroke, the YZ400F, for 1998. This is the machine that started the four-stroke revolution in motocross. He …

2013年8月30日 · Reading some old bike mags and came upon thos article about the original yzm400 Doug Henry supercross works bike. Man, this is still one of the best looking 4 strokes ever built; probably one of the best looking bikes of any kind. Yamaha ruined the production bike by using the dogshit ugly plastic that cane stock on the production bikes.