In 1980 Dutch privateer ‘Jumping’ Jack Middelburg won the 500cc Dutch TT on a Yamaha TZ 500 G built by the famous Dutch frame builder Nico Bakker. It marked the sole 500cc Grand Prix victory for Yamaha’s production racer.

Yamaha’s TZ 500 was a production racer for privateers based on the 500cc 0W45 factory bike with which American Kenny Roberts had won three straight 500cc world titles. Yamaha had decided to build its ‘customer racer’ following the success of Suzuki’s RG 500 production racer, a direct descendant from Barry Sheene’s world championship winning machine. The TZ500 cost $14,000 dollars and delivered a power output of about 110 bhp at a dry weight of 135 kilograms.

TZ 500 customers complained about the bike being underpowered and ill handling leading to the teams trying everything to improve both power output and handling. Jack’s mechanic Adrie van den Broeke tore apart the entire engine in search of reducing the 20 horse power deficit compared to Roberts’ 0W45 factory racer. But the most visible improvement came from Dutch frame builder Nico Bakker who managed to produce a sweet handling custom built tubular steel frame.

With Kenny Roberts having won all previous rounds up until Assen, the sight of home racer and privateer Jack Middelburg on pole position for the Dutch Grand Prix was quite extraordinary. Not that Middelburg could take advantage of his starting position; his mangled legs from previous accidents meant that he could barely push start the bike. Losing almost 20 positions at the start on a half wet track the Dutchman set off on slick tyres after Roberts and it took him just one lap to catch the leading group of Roberts, Mamola, Cecotto and Rossi. After 3 laps he managed to pass the American for the lead and never looked back to take victory by a huge margin.

Jack Middelburg went on to ride Suzuki’s and Honda’s in the world championship taking his second Grand Prix victory in Silverstone 1981 in front of Roberts and Mamola. Middelburg sadly succumbed to his injuries following a crash at the Dutch street circuit of Tolbert in 1984. His actual race winning TZ 500 will take to the Assen race track during the Classic GP in the hands of Dutchman Gerard Kampen. A second TZ 500 will be run by Bob Keller from Brazil.