With Phil Aynsley
Suzuki’s original entry into the 500cc class came in 1968 in the US with the XR-05. The motor was a modified unit from the T500 Titan/Cobra road bike.
1974 Suzuki XR-05 Mk III
It wasn’t until 1971 that the XR-05 appeared in Europe with Aussie Jack Findlay winning Suzuki’s first 500cc GP at Ulster that year. Output had risen from 63 to 71 hp over the intervening years.
The Suzuki XR-05 first appeared in the hands of Aussie Jack Findlay winning the Ulster GP 
1974 Suzuki XR-05 Mk III
A water-cooled version, the MkII, appeared in 1973 with triple disc brakes, larger carburettors and on works bikes, a six-speed gearbox, while power was 73 hp.
Power output on earlier models was 73 hp but evolved up to 80 hp 
1974 Suzuki XR-05 Mk III 
The XR-05 Mk III filled the gap before the introduction of the RG500
In 1974 the MkIII arrived as an interim model, intended to be used until the new RG500 square four was available. The MkIII had revised cylinders with a squarer look and laid down rear shocks.
1974 Suzuki XR-05 Mk III 
Square cylinders were a point of note on this model
Only 15 MKIII’s were constructed with the bike seen here number 15. This bike has been fully restored although all the paintwork is original apart from the fairing. Care was taken to use as many original parts as possible.
1974 Suzuki XR-05 Mk III 
1974 Suzuki XR-05 Mk III
The last of the MKIII bikes were delivered in 1975, by which time output was up to 80 hp at 8900 rpm. Dry weight was just 140 kg and top speed had reached 257 km/h.
1974 Suzuki XR-05 Mk III 
1974 Suzuki XR-05 Mk III 
1974 Suzuki XR-05 Mk III 
1974 Suzuki XR-05 Mk III 
1974 Suzuki XR-05 Mk III 
1974 Suzuki XR-05 Mk III
Source: MCNews.com.au