Ask any Suzuki sportsbike rider for the name of a great Japanese tuning house, and all will say Yoshimura. But what you might not be aware of is that there are actually two Yoshimura companies. The first, Yoshimura Japan, is based in Aikawa and they produce exhaust system, engine parts and other tuning parts. Fukuoka is where the metaphorical grandaddy of tuning started. Hideo 'Pop' Yoshimura began tuning the motorcycles of American airmen based in Japan after WW2.
Popp had been trained as an aircraft mechanic during the war, so he had a load of knowledge on how to tune the 50s-era motorcycles used by the bored USAF personnel. Put yourself in their shoes – you have a load of guys with motorcycles, plenty of spare time, and a 3.2 kilometer runway. How could you not start racing up and down it? And how could you not start messing with the motorcycle – especially if this crazy Japanese guy could get a stack more power out for you?
The second part of the Yoshimura story probably owes its existence to this early link with the US. Hideo went to the US in 1973, and began the expansion that led to the industrial unit. Yoshimura R&D of America Ltd is based in a cluster of large, anonymous sheds in Chino – a hard-baked, dusty, urban sprawl on the edge of Los Angeles. Yoshimura builds as much of its products in house as it can – so the solid flanges that bolt on the cylinder head are machined from solid blocks by huge CNC machine; stamping machines stamp out shaped end-caps, and angled exhaust hanger brackets are sliced and bent by hand from large strips of aluminum. Computerized tube bending and cutting machine the size of a city bus churns out a series accurate cut, shaped and bent sections of header and collector pipe, ready to be welded into full exhaust systems. Only anodizing and carbon fiber production is “currently” contracted out – these are specialist areas which are best left to firms with the infrastructure to do the job.
Yoshimura exhaust systems are made in Japan and the USA. We are told that both teams develop their product ranges separately – so there could be both an American and a Japanese pipe for a particular motorcycle, each with a slightly different specifications. One way of telling which type you have is to look for the flag on the exhaust nameplate – most USA pipes have an American Stars and Stripes, Japanese pipes have the Japanese flag.