Letter From Japan
LETTER FROM Japan
ROUNDUP
KOICHI HIROSE
Turbo FZ
Turbocharging keeps reappearing, and sometimes in the least expected places. Like in a custom shop in Japan, which has built a turbocharged Yamaha for F1 roadracing.
FIM regulations limit displacement of turbocharged engines to half that of normally aspirated engines competing in the same class.
So the Yamaha FZ400R on which this turbo racer is based required a displacement reduction to 375cc so it could compete with the 750cc four-strokes that run in the Japanese FI class. This was accomplished by reducing the bore from 54 to 52mm, and leaving the stroke standard.
KKK in West Germany made the turbocharger, a special-order product with a remarkably small turbine. Feeding the turbocharger are four 12.2-inch-long header pipes that are bent into meandering shapes to hold that distance constant. Incoming air is pressurized by the turbo, and then blown through four 30mm CV carburetors. A blow off-valve allows adjustment of the boost.
With the help of all this added intake plumbing, the power output for the FZ is above 100 bhp. In an actual race, however, the bike failed to finish because the transmission and clutch weren’t able to withstand the increased power.
Honda Tourist Trophy
A t present in Japan, “replica models” of modern racing motorcycles are enjoying overwhelming support by race fans, and the variations of this theme are the main trend.
On the other hand, there is a counter trend enjoying a deeprooted support: big Singles. Yamaha is the most vigorous proponent of this type of machine, offering the SR400 and SR500, along with the recently announced SRX400 and SRX600. Honda also has been influenced by this trend, and has entered the market with the GB400 and 500. (GB? Great Britain, of course.) Careful market research preceded this announcement.
Honda is seeking a particular image with the GB series: that of the big Single racer that won the TT races at the Isle of Man in the early 1960s. Consequently, the GBs have a single-cylinder engine (based on the radial valve XL/XR dual-purpose/enduro engine) surrounded by 1960s bodywork, and carry the name “Tourist Trophy.”
Because these models are meant for the so-called “manias” (Japanese terminology for motorcyclists who fit somewhere between fanatics and dedicated enthusiasts), it is interesting that Honda chose to build them. In recent years, Honda believed that this market was too small to contribute to the company’s goal of expanding its market share, especially after the sales failure of the FT400 and FT500 Ascots. Honda’s renewed interest in big Singles indicates that the company must now believe the market is expanding, even if the pace of expansion is not fast. And it’s likely that the Tourist Trophy series will considerably hasten that growth.
