Built with parts from bikes spanning six decades, this tribute to the might XR750 is a testament to the Sportster’s prowess as a platform for customization.
Just yesterday, we lauded the Harley Sportster as one of the most customizable bikes on the planet, citing its simple layout and a vast aftermarket as reasons. Today, we’re looking at a vintage Sportster that illustrates that point with nostalgic flair (as if we needed convincing).
You’re looking at not one, but two classic Sportsters: a 1966 Harley-Davidson XLCH Ironhead motor paired with a heavily modified 1979 XLS 1000 Roadster frame, supported by a diverse array of recycled Harley, KTM, and Ducati parts.
This glorious Sportster bitsa is the work of Michael Middeldorff, who operates out of Munich, Germany, as Motonaut—a cheeky reference to the Argonauts in Greek mythology. Nicknamed ‘Iron Maiden,’ this bike is his personal tribute to the legendary Harley XR750 flat track racer, reinterpreted with a handful of unique details.
At first glance, the Iron Maiden looks like a carefully restored factory race bike from yesteryear. But don’t let its delightfully minimalist vibe fool you—there’s a lot going on here.
The project started with the XLS frame, which was de-tabbed, truncated at the rear, and treated to a new backbone and steering neck. A set of 35 mm Ceriani GP replica forks sits up front, fitted with a cartridge kit that offers full adjustability, while custom-order YSS shocks prop up the rear. The forks came from CR-Suspension, who also supplied a set of ultra-wide yokes.
The wheels are a mixed bag, with 2.5×19” Harley Hydra-Glide hoop up front and a 3.0×19” V-Rod front rim at the back. The front hub is a 1974-spec Harley part, the front brake caliper was lifted from a 2018-model Harley-Davidson Street 750, and the master cylinder and lever came from an old KTM quad. A 1990s KTM LC4 Brembo caliper does duty out back, triggered by a Ducati 916 master cylinder and pedal on custom mounts.
When it came to the engine, Michael opted for reliability over outright performance. The 59-year-old XLCH power plant was rebuilt and upgraded with an electronic ignition and a Lithium battery. A NOS Screamin’ Eagle carb from the 80s was installed, along with a pair of simple drag pipes; the air cleaner cover, primary cover, and exhaust pipes were all ceramic coated.
The Sportster’s bodywork is classic Harley flat tracker fare. Michael snagged a fiberglass and tail section, splashing them in a timeless orange livery. The oil tank and strap were made from scratch, with a buddy lending a hand on the welding.
The cockpit features LSL handlebars, period-correct H-D grips, Motogadget micro-switches, and a digital Motogadget motoscope mini speedo. Michael has everything he needs to run the Sportster on the street, too—including a clip-on headlight and Kellermann LED taillights and turn signals.
Michael buttoned the Iron Maiden up in time to debut it at a very special event—the 10th Flat Track Invitational at Valentino Rossi’s VR46 Motor Ranch in Tavullia, Italy, in the presence of American flat track legends Scott Parker and Bill Werner.
“It was a short premiere, because I lost spark after just a couple of laps,” he recalls, “but it was the best possible way to ride the bike for the first time.”
Motonaut Instagram | Images by, and with thanks to, Marc Holstein
