KTM 450 EXC customized by Walt Siegl

KTM 450 EXC custom motorcycle by Walt Siegl
Walt Siegl is the embodiment of a life well lived. A former motorcycle racer, he now builds high-end Ducati customs in a picturesque New Hampshire mill town. His impossibly beautiful Leggero sportbikes are sought after and shipped all over the world.

Walt occasionally likes to mix things up though, and this is one of his most unusual creations. It’s a modern KTM 450 given a vintage motocross flavor without losing any of KTM’s legendary off-road prowess.

KTM 450 EXC custom motorcycle by Walt Siegl
The commission came from a client who already owns several of Walt’s creations. “He asked me for a motorcycle that he can take off road on occasion,” says Walt, “and left the choice of donor bike up to me.”

Walt’s interest was piqued. As a boy growing up in Austria in the 1970s, he would watch the local motocross races with his father. It was a time when KTM was rising to prominence, so we can assume that Walt felt more than a little national pride.

KTM 450 EXC custom motorcycle by Walt Siegl
“I’m even more impressed by today’s KTMs, so I decided to use the Austrian machine as a platform,” says Walt. But there was a catch. “My client is an extremely successful designer and businessman. His product has a high grade of hand-built quality to it. So he’s suspicious of anything that smells of computer design.”

The solution was to rework the razor-sharp edges of modern KTM styling. Could Walt give the bike timeless lines, ones that would sit well next to his client’s beloved Hodakas and Maicos? “I had my work cut out,” he notes wryly. “But I wanted to capture the visuals of past times, while taking advantage of the high tech performance of today’s KTMs—snorting, rowdy machines that perform like a shotgun.”

Walt started by shaping a mockup tank in foam, and had the mockup scanned. A hardwood plug was then machined, so Walt could make the fuel cell in aluminum. He also built a new aluminum subframe, but only after careful measurements—to allow enough suspension travel. The side panels are made of the same 60-series aluminum as the tank.

KTM 450 EXC custom motorcycle by Walt Siegl
There’s a new aluminum seat pan too, with the seat core shaped in medium density urethane. It’s finished in leather by Vivian Smith, who does all Walt’s upholstery work.

The handlebars are vintage-style aftermarket items, and the rear fender is from Air-Tech, originally created for a Maico application. Walt made the front fender using fiberglass, and installed a headlight and shroud from eBay, extensively altered to fit.

The suspension and engine remained untouched: it’s hard to improve on the dynamics of a KTM 450, even if it’s a street legal EXC model. Walt did build a new muffler from stainless steel though, and re-jetted the Keihin carb.

KTM 450 EXC custom motorcycle by Walt Siegl
The paint is simple and effective. “I wanted to juxtapose the vintage design elements with contemporary graphics in bright colors—as a reminder that the bike is a modern machine, after all.” The renowned Robbie Nigl of Peach Pit applied the colors.

The result is curiously appealing—a custom that’s been stripped back to its functional basics. There’s a love-it-or-hate-it aspect to the styling of modern KTMs—but it’s hard not to love what Walt has done.

Check out previous Walt Siegl builds on his stylish website, or follow his news via Facebook.

KTM 450 EXC custom motorcycle by Walt Siegl