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Bike Tale - Posted 10th June 2015
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Royal Enfield 75cc and 98cc Prototypes

Two experimental lightweight bikes dating from the mid-1960s were sold at auction earlier this year. RC reader Geoff Lewis knows all about them, and several others...

If you’ve never heard of a 75cc Royal Enfield five-speed commuter bike, that’s because it didn’t go into production. But several prototypes were built and entered circulation – and a couple survived to be auctioned earlier this year. Documents show that Royal Enfield’s chief draughtsman, Reg Thomas, confirmed that the first prototype was powered by a five-speed Villiers-built engine, and equipped with unusual rubber-block rear suspension. It was tested during 1963 and covered around 1000 miles by November of that year, and Enfield were happy enough with it to plan for the introduction of a six-speeder, 75cc or 98cc, with conventional rear suspension, within a couple of years.

Royal Enfield 75cc and 98cc Prototypes

One of the surviving bikes which was sold this year does indeed have ‘normal’ rear shocks so must have been a further development of the initial experiment although it kept the five-speed gearbox. It was first registered in 1968, two years before Royal Enfield went out of business, and was first owned by one Frederick Reginald Lewis (remember that name!). The bike has been recently ‘refreshed’ with re-plated brightwork and a replacement saddle, and was sold for £3450 with a spare engine, an MoT and its original paperwork.

Royal Enfield 75cc and 98cc Prototypes

Enfield also experimented with a step-thru prototype at the same time. Unlike the lightweight motorcycle, the step-thru used a modified Royal Enfield Ensign 75cc engine with four-speed gearbox. It sold for £2645, and the report on the auction in RC134 attracted the attention of Geoff Lewis, who takes up the tale of the prototype motorcycle…

Royal Enfield 75cc and 98cc Prototypes

I once knew this bike well. My uncle, Reg Lewis, and his partner Tony Donadel of L&D Motors in Bristol bought a job lot of prototypes and spares in 1967 or so, and this bike was among them. There were note-books with each bike and the year 1963 comes to mind as the date of their development. The 75cc five-speeder was a lovely little bike to ride and would reach an indicated 60mph. The hubs and brakes were bought-in alloy units common to many small bikes of that time. The gear cluster and clutch were made by Enfield's usual supplier, Albion, and there were various unmachined alloy castings with the bike which make me think it was made in-house at Enfields. I have not heard before of any Villiers link but could be wrong. I cannot recall any failings with the bike and it was surely ready for production. The bike was on display in L&D for a few years.

Royal Enfield 75cc and 98cc Prototypes

There was a slightly older and well-used 98cc version of the bike in the same lot. On this example there was a steel petrol tank concealed under the fibreglass seat and tank cover unit, while on the 75cc bike the fuel was contained in the fibreglass seat / tank assembly. The 98cc engine needed some parts, all of which would need to be specially made. So my uncle gave me the bike, less engine, together with a virtually unused, one-off, three-speed 75cc Ensign engine which came with the prototypes. We altered the engine mounts and fitted this engine. The Miller ignition system, however, was most unpredictable and the engine itself not a patch on the five-speeder.

Also among the prototypes was a 175cc, five-speed, chain-driven OHC, wet-sump machine which looked at first glance a bit like a Continental. The bike evidently went quite well, albeit a bit noisy mechanically. The only camshaft and followers with it were well worn and in need of re-manufacturing, so the engine was stripped. The wet-sump set-up tackled some of the failings of the Crusader engine and this, together with the many other improvements, might have made it a good seller for a few years. The prototype was eventually rebuilt and sold on at some point.

Royal Enfield 75cc and 98cc Prototypes What's that hole for?
Ordinary Enfields on Now...

I used to run errands for my uncle on the 75cc bike, often with a crank or barrel or something of that ilk stuffed into a greasy old canvas gas mask bag, and used it sometimes to ride to school in Clifton. This was where the Ensign engine let me down. It did go particularly well when ridden along the banks of the River Avon at night, I recall. Better air?

At about the same time, Enfield evidentially dropped in a couple of experimental Series 1 Interceptors which had been converted to wet-sump lubrication as forerunners to the Series 2. The bikes were given a quick thrash and went well (55bhp at that time was not to be sniffed at), but the alloy welding of the sumps to the bottom of the crankcases was evidently not aesthetically pleasing… My uncle did not use those exact words and the bikes were sent straight back to Enfields at Upper Westwood.

Royal Enfield 75cc and 98cc Prototypes

In 1969, aged 16, I had the chance to buy one of two new Continental GTs which were on sale in the shop. The price was £190 and as the RRP at that time was £293 I quickly bought one on hire-purchase. The bike was, as a somewhat bizarre marketing feature, supplied with a complete four-speed gear cluster FOC as the five-speeders fitted as standard to the GTs were notorious. Sure enough, within a few thousand miles various false neutrals on the five-speeder gave me a few frights and so the four-speed cluster went in. The GT went well and looked simply fantastic – a 16 year's dream bike at that time.

Words: Rowena Hoseason and Geoff Lewis - Photos: Bonhams auctioneers


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