The People Behind Yamaha Factory Racing

When people think “development”, they often picture styling and design. But there’s another crucial part of the process: evaluation. Inside Yamaha’s First Vehicle Experimentation Department (YZ Gr.), evaluation means riding the bikes—testing engines and chassis in the real world, then judging what works, what doesn’t, and what needs to change. 

If the frame is the bike’s skeleton, the engine is its heart—and Kitahara Naotetsu is the coordinator overseeing the full scope of YZ engine evaluation. Engine testing isn’t just ride feel. It includes measuring engine-only performance, checking functionality (oil circulation and pressure), evaluating reliability through durability tests, measuring noise to meet race regulations, assessing starting, and more. Kitahara describes himself as a “jack-of-all-trades”—someone looking at everything, managing everything.

Welding rarely gets the spotlight, but for Otohito Yamazaki—an engineer with deep welding expertise—it’s a core part of YZ450F quality and reliability. Yamazaki first became involved with the YZ more than 20 years ago, around the launch of the YZ450F. After time working on supersport models like the YZF-R1 and R6 and handling frames for overseas models, he returned to the YZ—setting and resetting welding on the assembly line, touching up welds, and performing final inspections. He moved into his current department four years ago.

Takayanagi Kenji works in quality control. His role is to establish, maintain and manage quality standards for each new-model assembly process. He plans and implements measures to prevent defects and recurrences, and drives improvement activities by analysing quality data. Two influences led him to Yamaha Motor. One was his older brother, who worked for the company and was involved in motorcycle inspections. The other was personal history: Takayanagi attended Yamaha Motor’s soccer school as a child—back in first grade, over 30 years ago. That familiarity helped shape his desire to join.

The YZ series of motocross competition models is sold globally—strongest in North America, but also spanning South America, Europe, Oceania and Asia. The riders are just as varied as the map: professionals in AMA Supercross, the Motocross World Championship and All Japan, plus weekend riders enjoying family rides or solo sessions. Some stay with YZs for life. Some ride them simply because it makes life better. And the YZ, in turn, is built by people inspired by those riders.