Endurance style: Walt Siegl’s custom MV Agusta

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
Walt Siegl, I’d wager, is the world’s best custom Ducati builder. But it turns out that the machines from Bologna are not his only love.

“When I was a boy in Austria, long before I’d heard of Ducati, I considered the King of Persia a man of good taste: he had nine MV Agustas,” says Walt. “MV was winning everything at that time—Italian jewels that beat the British and the Americans. There were posters of Giacomo Agostini everywhere.”

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
The romance of MV Agusta has endured over the decades, and Walt has finally built a machine based around the superb MV triple—specifically, the Brutale 800.

It’s called ‘Bol d’Or’, and it’s got a distinct endurance racer vibe. “I have a soft spot for the raw brutishness of the endurance bikes of the early ’80s,” says Walt. “The big tanks that hold 20 liters or more, the large fairings to tuck under, the offset headlights for night riding, and so on.”

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
“But my heart is still with the small Italian bikes that have curves and a sexy waistline. So I tried to combine my attraction to all these elements in one bike.”

He’s succeeded. If the Varese factory decided to go down the same retro route as Triumph and BMW with the Bonneville and R nineT, they’d probably come up with something very close to the Siegl ‘Bol d’Or.’

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
Walt describes his client as “A very fast guy who has a soft spot for classic race bikes.” But unlike the Leggero Ducatis, this MV does not have a hand-built chassis.

“I wanted to stick with the factory chassis,” says Walt. ” I didn’t want to undo something that’s so good. The challenge was to design completely new bodywork around the existing frame and other very specific design elements—like the cast aluminum engine plates and swing arm.”

Walt used foam board to create the principal shapes, shaving a foam core and building it up with automotive clay. He then created a rudimentary subframe and fairing stay, positioning the new body parts and ram air system.

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
“A ram air system gets the best out of the highly tuned 3-cylinder engine. I increased the outer diameter of the air intakes and put the air inlet placement onto the front of the fairing.”

To get the most out of these mods—and improve torque and horsepower—the ECU was flashed with a fully tunable performance program.

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
John Harvey of FuelCel then took the molds and turned them into Kevlar composite. (“Kevlar has high structural integrity and resistance to impact, compared to the brittleness of a carbon fiber weave.”)

The weight savings are considerable. The new tank holds a hefty 20 liters of gas, but weighs just 3.5 lb. And that includes the stock fuel pump and aluminum fuel cap.

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
“In my experience, saving weight wherever you can, rather than tearing into an engine to get more horsepower, will always result in a better performing motorcycle,” says Walt.

“Buying a set of magnesium wheels, for example, will make your bike lighter, and turn easier. And it’s cheaper than putting money into engine performance.”

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
The entire bodywork of the Bol d’Or weighs just 8.5 lb. That includes the front fender, the upper fairing, two lowers, and the tail section.

Even more weight reductions come from the new aluminum subframe, the lightweight SC Project exhaust system, and Walt’s own adjustable rearsets—machined from 7075-T651 aerospace grade aluminum.

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
At a track day, Walt was able to compare the weights of a factory F3 and the Bol d’Or on the scales. The stock F3 weighed in at 421 lb., and the Bol d’Or came in at 340 lb.—with a gallon of fuel, and oil in the crankcase. (That’s 155 kilos in Euro parlance.)

Not surprisingly, the bike is seriously fast. “It’s a ferocious beast that screams like a F1 car, and tears your arms out of the sockets when you grab big handfuls. It sounds so good it gives you chills.”

The Walt Siegl Bol d'Or: a modern MV Agusta with a dash of retro style.
Tempted? Though the Bol d’Or is based on the Brutale, future versions can be built using any current MV triple. If you want a truly personalized machine but don’t want to sacrifice performance, you know who to call.

Walt Siegl | Facebook | Instagram | Images by Douglas MacRae | Instagram