At this year’s Goodwood Festival of Speed, Yamaha showcased the XSR900 DB40, a racing prototype—based on the XSR900. The DB40 in name hints at celebrating 40 years of the Deltabox chassis. For those wondering, the ‘Deltabox’ is an amalgamation of the word ‘Delta’, the fourth letter of the Greek alphabet—represented by a triangle and the word ‘box’.
From the side view, the Deltabox is formed of a triangle linking the head pipe to the swingarm pivot, while the cross-section is box-shaped. This relationship between the steering head and the pivot point is said to offer outstanding rigidity and feedback where the rider will need it the most. The cross-shaped box section allows for a greater surface area while offering lighter weight and a higher level of rigidity, the company added.
Yamaha debuted the Deltabox chassis in their 1982 YZR500 OW61 Grand Prix machine, while the frame’s first appearance in a production racer came just 3 years later, the TZR250, bringing the characteristics of the YZR factory race machinery to the road. The Deltabox has since become synonymous with Yamaha’s supersport models, including the iconic R1 launched 25 years ago.
Since this is a prototype, Yamaha didn’t share a ton of information besides the obvious ones we could see here. However, the company was kind enough to let us know that the motorcycle is powered by an award-winning 890 cc ‘CP3’ triple-cylinder engine housed inside the aforementioned latest version of the Deltabox frame.