Anyone who has raced motorcycles or spun spanners in a pit lane will know that track bikes are a work in progress. They?re mobile test beds, because shaving seconds off lap times is the only way to stay ahead of the competition.
The mechanics at the Japanese workshop AC Sanctuary know this. For the past three years, they haven?t just been building muscle bikes for the road?they?ve also been tuning and modifying this incredible Kawasaki racer.

The core of the bike is a Z1000 engine, which delivered 85 horsepower at the crank when it left the factory in 1977. It now measures 152 hp at the rear wheel on the dyno. That makes this the fastest air-cooled bike on the Japanese classic racing scene, and it also holds the lap record for its class at the Tsukuba Circuit. According to AC Sanctuary founder Hiroyuki Nakamura, the Z1000 will race for the last time in 2022. ?We didn?t enter any races in 2021, due to the spread of the virus. But we are planning to race in November this year, in the T.O.T. [Taste of Tsukuba] event.?

The Z1000 will line up in the Super Monster Evolution class, which is the fastest class for air-cooled engines. ?The race is run with the Hercules class, the fastest water-cooled class?because we’re trying to beat those high-powered machines as well,? says Nakamura. ?After that race, the challenge will come to an end.?
Most of the Z1000?s recent development has centered on the DOHC two-valve four-cylinder engine, which uses a carefully ported GPz110...