This is a good read, some Suzuki GP machine history from a NATS forum member. I love the Skoal Bandit sponsorship.
"When Suzuki retired from 500 GP at the end of 83, the old square four ( created in 73) was no more competitive against the Honda and yamaha V4.
therefore they continued to provide support to Heron in UK and Gallina in Italy with work engines and suzuki alloy frames.
In Uk, the Heron team decided to invest in a new frame to reduce the weight and ordered 2 prototypes to Nigel Leaper in Cambridge.
The first prototypes were "white" with aluminium sheets climbed on a honeycomb material from Ciba geigy.
6 other bikes were build after the prototypes.
in 84 they used XR40 engines; in 85 XR45 with exhausts valves and in 86 the last square four : the XR70RV with reed valves instead of disc valves.
in 84 and 85 they used alloy swinging arms and suzuki forks but in the middle ot 86 they changed for a carbon swinging arm and WP inverted fork.
the weight for the 86 bike was around 110 kgs and the maximum power was 148 HP due to the UK development especially in exhausts, heads and air-boxes.
The problem was that the factory was not interested with carbon ( too far from the production road bikes) so at the beginning they were not helpful with the Uk team but the results were better than the Gallina's bikes so in 85 they give better engines and support to Heron.
The frame was too stiff: it was the most important problem because the bike was so light.
The first pilot in 84 was Rob Macelnea,
In 85 Paul Lewis came in the team and Macelnea left for Yamaha.
In 86, Paul Lewis (33) was still in the team with Niall MacKensie (47) and in the middle of the season Kevin Schwantz (34).
For the last race ( GP San Marino at Misano) MacKensie was in the first row.
Kevin Schwantz won his first point in 500 with one of the 86th bike in SPA.
At the end of 86, Suzuki announced his return as official team with the new XR71 V4.
A batch of « carbon bikes was sold at the end of 86 to gerhard Vogt in Germany and two 86th bikes with XR70RV to Frankonia team in swiss with Wolfgang Von Muralt as pilot."
Photographs and text via North American Two-Strokes forum.