Yamaha XT630 Supermoto by 86 Gear Motorcycles

A customer of 86 Gear came in with his well-used 2000 XT600 motorcycle—his daily ride. The owner’s goal was to get a 1994 Yamaha TT600 dirt bike and use its parts to enhance his XT. When 86 Gear found a TT600 in excellent condition, the owner decided to simply use the TT as his primary ride. That changed the nature of the XT600 build—the owner wanted a stripped-down supermoto bike for some wild rides around town. After an 18-month wait, he got just that.

The air-cooled SOHC engine got immediate attention, with Motoritz providing guidance. The XT received an early TT600 camshaft, plus a higher-compression piston and new connecting rod, which bumped the displacement up to 630cc. Dual Mikuni TM34 flat side carbs were recruited, with porting performed to accommodate the expanded airflow. Air is cleaned by K&N tapered conical filters, and the spent gases escape through a custom exhaust with dual mufflers that recall the Ducati Scrambler. Upgraded clutch springs and hydraulic actuation helped handle the newly created power. To manage the additional heat, an oil cooler from a 1984 Yamaha XT600Z Ténéré was installed.

“Thanks to the carbs and the camshaft, the bike reacts very sensitively to the throttle,” Boosen explains. “Without a gentle hand, you can end up on the back wheel in an instant. On the road, its performance matches modern sportbikes.”

As always, when you have more power, you need to improve the chassis. The XT630 is the recipient of a YSS shock, Wirth progressive fork springs, and a Kern-Stabi Motorradtechnick fork brace. The subframe is modified for the locally sourced 4Drive custom seat, with Adrian Figura from Warsaw’s Scrambler74 handing the welding work.

The wire-spoke wheels are of legitimate supermoto caliper. SM Pro Wheels supplied the wire-spoke Platinum wheels, which are shod with Dunlop Mutant tires—a 120 in the front and 150 out back. A Nissin front caliper is mounted on a fabricated bracket, with a full-sized street rotor feeling the grasp.

Essential styling touches include a Motogadget speedometer and bar-end turn indicators, an offset-mounted Suzuki GN125 replica headlight, and Highsider taillight. A custom wiring loom was created, and a Li-ion battery delivers the power.

A brilliant throwback inspiration is the 1983 Yamaha XT500 fuel tank. The aluminum tank did require some rough persuasion to fit in, and it looks fantastic.

“When it comes to motorcycles, the adage’ form follows function’ holds for me as a custom builder,” Christian Boosen reveals. “Although the aesthetics play a large part in my design process, the essence of every custom motorcycle, no matter how stunning, is that it’s meant to be ridden after all! That’s why I start every client brief with the intended purpose of the machine. It will take time. We will sit down and talk about ideas, dreams, and wishes, adding safety features and performance upgrades. Intensive talks about the details and how to build the bike are essential to make it special and one of a kind.”

Doubtlessly, the 86 Gear Motorcycles 59th Gear Yamaha XT630 Supermoto is a distinctive build.