Masumi Tsuchino of Japan’s Infinity Motorcycle has crafted “BT6,” a stark and purposeful board tracker that reimagines American racing history through a “what if” lens.
Commissioned by S&S Cycle for their 2025 Vintage Tour, the build asks what a 1920s board track racer might have looked like if S&S had existed during the sport’s golden era. Tsuchino, a former Toyota mechanic with a penchant for historical precision, utilized a modified 1936 Harley-Davidson Knucklehead frame and a set of vintage girder forks to create a silhouette that feels like a recovered artifact.
This Custom Harley-Davidson Knucklehead Is Truly Something Special
The machine avoids modern flash, opting instead for a period-sensitive finish by Rio Studio and New Classic Painting that allows its raw, mechanical geometry to command attention.
At the heart of BT6 is a high-performance 93-cubic-inch S&S KN93 Knucklehead engine, treated with custom surface finishes to mirror the aesthetics of a century ago.
While it looks like it belongs on a vintage timber oval, the bike hides a suite of modern upgrades for reliability, including S&S electronic ignition, a Super E carburetor, and a Baker Drivetrain 6-into-4 transmission. The rolling stock reinforces its early racing stance with large-diameter clincher rims—22 inches up front and 20 inches at the rear—paired with a Brooks B17 bicycle saddle.
By blending show-quality craftsmanship with a bulletproof, modern drivetrain, Infinity Motorcycle has produced a “tasty knuckle sandwich” that bridges the gap between historical fiction and contemporary engineering excellence.
Sources: Pipeburn, Infinity Motorcycle
