YAMAHISTORY.COM
The early history of Yamaha Racing 

​Three months after Daytona, a batch of just 10 x RR 250cc customer machines, started to appear in the US as a prototype for a new breed of Yamaha that customers had eagerly been waiting for; a bespoke built, over the counter Production Racer. 

West Coast Yamaha Distributor Frank Cooper, received the machines from Japan and it is he who can credited with the choice of colour scheme, as legend has it that as Yellow was his favourite colour, he chose it for the new machines. The colour of course was again chosen by the US Factory Team 8 or 9 years later, the Yellow, Black & White Speed Block design by custom car painter Molly Sanders, made famous by the many victories of Saarinen, Carruthers & Roberts etc. Yellow though, was not the Yamaha factory's intended colour scheme. Recent findings on more than 1 surviving machine shows that under the vivid yellow is a muddy red-brown, following along the lines of the YDS1R Fuel tank colour but with a more glossy finish. One can easily understand the marketing decision to choose Yellow, or indeed ANY colour other "muddy" brown !  

Cooper sent several of these machines across to his counterpart distributer George Caswell, for sales on the East Coast at Broomall, PA. It was reported by Caswell to Frank Munz that the machines would just arrived from Japan without notice and without knowing how many more would be sent across. 

The "Yellow Tankers" or "Yellow Road Racers" as they became known received an improved, slightly stronger frame than that of the Daytona works machines. They had an additional length of tubing wrapped and welded over the top of front downtubes and onto the headstock to beef the assembly up, a feature which was to stay on the frames from the Yellow Tanker right through to the end of the TD1 range. Position of the front fairing/tachometer mount was altered and a little less attention to detail was applied to the welding than the works machines, possibly indicating a different grade of steel.

The rear brake was altered slightly with the new machine featuring a SLS rear hub with a forward facing vent as opposed to a TLS with a downward facing vent on the works machine (as seen on the YX18 prototype) and the exhaust system differed too, with the header pipes converging under the engine on the Daytona machines as the YDS1R and diverging on the production machines and the subsequent later TD1 model.

The YDS1 based Asama spec YX24 engines were now fitted with alloy barrels but retained the Asama YDS1 cylinder heads. MC2RY ignition remained, as did the Amal-Mikuni 27mm carburation. The float chambers though were now affixed to the rear of the engine as opposed to brackets on the frame.