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Fast Family: A WR400 from a father-and-son team

Yamaha WR400 flat tracker by AMP Motorcycles
At its heart, motorcycling is a solitary pursuit. But it also brings people together, sharing their enthusiasm and skills when the hand is not on the throttle.

We love stories about kindred souls working together, especially when they involve families—because too often, family anecdotes dwell on parents being unhappy with their offspring heading out on two wheels.

Yamaha WR400 flat tracker by AMP Motorcycles
That doesn’t apply to the German father-and-son team Michael and Allen Posenauer, who are based in Offenbach and run AMP Motorcycles. They’ve just finished this very cool Yamaha WR400 F Enduro conversion, and their enthusiasm is infectious.

“We’re doing this as a hobby—as our ‘father/son’ thing,” says Allen.

Yamaha WR400 flat tracker by AMP Motorcycles
“Nothing professional, just for fun. We’ve got a workshop in an old office building, and we work on our bikes after hours or on the weekends. It is great to spend time together with my dad.”

The WR400 was launched in the late 1990s, and was replaced after just two years. That’s despite rave reviews, with magazine road testers lauding it as ‘bike of the year’ and even ‘Bike of the Century.’

Yamaha WR400 flat tracker by AMP Motorcycles
That makes it the ideal candidate for a flat track conversion. At around 270 pounds fully fueled, and with plenty of tractable, low-end power, the WR should be a strong contender on the dirt.

“It’s our first ‘real’ flat tracker build,” says Allen. “We’ve already built a tracker based on a Honda FT500, but that was for the street.”

Yamaha WR400 flat tracker by AMP Motorcycles
Michael and Allen got bitten by the flat track bug last year, when they crossed the border to visit Lelystad—a 300-meter Dutch track with a fine, soft red gravel surface, similar to loamy ‘cushion’ tracks in the US, such as Lima.

Their friend Uwe of Hombrese Bikes located a 1999 WR400, and suddenly AMP was in business. They stripped off all unnecessary components, including those that made the Yamaha road legal, and all the plastic bodywork.

Yamaha WR400 flat tracker by AMP Motorcycles
The KYB forks were shortened a tad to level out the stance—and with almost twelve inches of travel, there was plenty of room for adjustment. Moose Racing rims—19 inches front and back—were laced to the stock hubs.

The rubber is Mitas’ H-18 flat track pattern (which incidentally, is also available in a road legal version).

Yamaha WR400 flat tracker by AMP Motorcycles
The stock WR400 has a lot of overhang over the back wheel, so AMP have trimmed the rear frame—and got the visual proportions spot on in the process.

The new bodywork is simple, angular and functional, and crafted out of 2mm aluminum. “It’s built freehand,” says Allen, “using bits of cardboard as templates. It’s super fast to dismantle. The front and side plates are also self made, using aluminum.”

Yamaha WR400 flat tracker by AMP Motorcycles
The seat pad is equally simple, and covered in a synthetic leather by local saddler Klaus T.

Peaky, unmanageable power is more of a hindrance than an asset in flat track, so AMP have left the WR400’s liquid cooled single cylinder motor alone. They’ve built a new stainless steel exhaust system though, terminated with a home-built muffler. And there’s a new radiator from the German aftermarket specialist Motea, as an insurance policy.

Yamaha WR400 flat tracker by AMP Motorcycles
The cockpit follows the ‘less is more’ principle, with virtually naked LSL bars hosting a ProTaper clutch lever and Vans grips (“because they are cool”). And the stripy, monochrome paint is a bare minimum job too.

“The paint job was done by us,” says Allen. You can tell his priorities were elsewhere. “It’s not A+, but it’s good enough for track use.” Mechanically, just about everything else was replaced with new OEM parts, or restored to original condition.

Yamaha WR400 flat tracker by AMP Motorcycles
This weekend, Michael and Allen will be returning to Lelystad, and running the WR400 in anger for the first time. Viel Glück, guys!

AMP Motorcycles Instagram | Images by (and with thanks to) Marc Holstein and Christine Gabler

Yamaha WR400 flat tracker by AMP Motorcycles

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