1966 Bridgestone 175DT

I always like to delve into earlier Japanese machines, especially examples that seem to be doing it smarter and better than the period opposition. This 175DT (Dual Twin) is no exception. The Bridgestone uses a parallel twin arrangement of their 90cc engine with the same 50mm x 45mm bore and stroke. It uses rotary valve induction and produces 20bhp, enabling it to run a quarter mile in 17 seconds and hit 70mph, pretty impressive for its small capacity. Bridgestone included an automatic oil pump with a variable output which was dictated by the throttle opening. More innovation is shown in the gearbox, which can be switched via a lever between a four or five speed. The five-speed gives an overdrive of sorts, providing performance and economy at higher speeds, while the four-speed arrangement worked in a rotary fashion; from top gear you could go straight into neutral before going back into first gear to set off again, all using a downwards action on the lever. With all this you can see how the Japanese were just doing these things better in the 1960s... Compare this to the BSA Bantam D10 of 1966; an old-fashioned design which still required the owner to premix the oil and fuel and BSA had only just introduced a four-speed box to the sports model at this time.