Supercharged Pre-unit Triumph Motorcycle for Free

When Free, our Pommy blonde bike rider, immigrated to Australia, she wasn’t going to leave her 1957 pre-unit Triumph behind.

THIS truly amazing supercharged Triumph was built by Simon of Bedsford Shire in England before being shipped to Australia when Free immigrated. Simon’s idea was to build a drag-style bike that not only looked the part, but it also had to go like the proverbial piece of flying excreta.

The T110 Triumph spent nearly a year in the workshop being progressively modified to cope with the job it was designed to do. It was not simply fine-tuning the motor to obtain maximum possible horsepower, but just as crucially, to devise a means of getting every ounce of that horsepower on the road where it belongs.

One of the first items on the list was the ultimate performance bolt-on—a Shorrocks C75 supercharger. Also a AMC Norton gearbox to suit.

The crankcases were highly polished by hand before they were fitted. It was cleaner than the day it left the production line in Meridan 30 years before. Otherwise, no alterations to the motor were necessary, not even a lengthening of the scavenger pipe.

Simon retained the original and remarkably uncracked 8-stud head and made manifolds to suit; although, with the benefit of hindsight, he admits that it was not a great idea as it blew a head gasket in its very first outing. A 9—10 stud replacement would be a sensible alternate.

The supercharger, for the moment, has been rigged up from a pulley bolted onto the engine sprocket. Not a ideal arrangement as the belt has a tendency to cover itself in grease thrown up from the primary chain, which, running open as it does, requires liberal coatings of the stuff in order to stop it coming apart at the seams. The only cure is, apparently, the fitting of a one-off extended crank and main shaft—a terrific idea but one which has been shelved for the time being.

Mechanicals aside, the construction of the Triumph proved to be relatively unproblematic. The motor is tilted forward to follow the line of the down tubes. The frame, in its unmodified form, hailed from Eurocustoms in Coalville, as did a lot of the other rolling bits and pieces.

The front-end is extended Triumph and the twin stoppers carry the Kawasaki brand name. The fender is a shortened Harris.

The overall colour is a special pearl mix over black which transforms itself when exposed to direct sunlight.

words & pics by Jules @ Top Gun

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