Twinline Motorcycles' sleek Yamaha RD350 custom

In the early 70s, the Yamaha RD350 set the motorcycling world on fire. It was light, rapid and unforgiving: in the right hands, it could comfortably see off a 750. In the wrong hands, it was a one-way ticket to the hospital. This restored and customized RD350 is the work of Seattle-based Twinline Motorcycles, and known as Project Goldhead in honor of the rare DG cylinder heads. According to shop owner Ian Halcott, the customer “walked into our shop with a basket case RD350 and about $5,000 in trick parts from Moto Carrera, Chinoy and others, and asked us to...