In an earlier column (Eric Offenstadt’s Kawasaki 500 monocoque racer) I made reference to the influx of two-strokes into the 500cc World Championship in the late ‘60s and early ‘70s, affording the privateers a cheap and competitive mount.
Here is another excellent example – the 1972 Hi-Tac Suzuki. It was the project of ex-Norton Villiers chief development engineer Peter Inchley who saw that water cooling was desirable for two-strokes and designed a thermo-siphon kit for the T500 road bike engine, before Suzuki’s own TR II became available in ’73.
In original specification, the kit comprised of the water-cooled barrels with cast iron liners which were removable for porting, a close-ratio gearbox, CDI ignition, Ni-Cad battery and expansion chamber exhausts.
The first year’s kit had a single Amal 38 mm carburettor (twin carbs were used later) which provided excellent flexibility with no noticeable drop in top end power. The CDI ignition allowed a 14,000 rpm limit.
The standard air-cooled motor made about 60 hp with the original kit raising that to 72 hp. Later twin carb versions made 82 hp.
This bike was originally owned by Barry Sheene who then sold it back to Colin Seeley, who in turn sold it to Charlie Sanby who achieved a third place in the 1973 Senior TT – possibly the last time a road engine made a GP podium?
The current owner has fitted an electric water pump to cope with the more relaxed pre-race procedures at classic racing events these days.
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