800cc Royal Enfield Interceptor prototype rides again

Allan Hitchcock's 800cc Royal Enfield.
(Allan Hitchcock Photo)

A prototype Royal Enfield 800cc twin-cylinder motor in a cafe style motorcycle certainly fires the imagination.

Factory tested in 1969 — at 128 mph — the 800cc motor was a development of the already impressive 736cc Series II Interceptor with its wet-sump lubrication, but with noticeably larger barrels.

What if Royal Enfield had gone ahead with production of such a motorcycle in 1970?

And what if such a motorcycle were produced today?

Allan Hitchcock of Hitchcocks Motorcycles Ltd. in the UK has one of the very few 800cc prototype motors. He has it installed in the frame of a Royal Enfield twin, and styled to match the motorcycle of 1969.

Hitchcocks displays the bike at events in the UK. I asked Allan to tell me more about it. He was kind enough to email this reply:

"The 800 engine arrived as some parts amongst a huge hoard of bits from the Royal Enfield dealer in Bristol in 1991. After many weeks/months of sorting through the parts I noticed that there were some odd shaped barrels and it was only the long skirts that gave them away as Enfield. This got me thinking and then checked some of the crankcases and one set of the Series II cases were different to standard along with some heads etc.

"At this stage I realized what it was and put them to one corner and forgot about them for some time. It wasn’t until some years later that one of our long time customers offered to put it together just to keep it together. All the key parts were there so it was just the task of putting the motor in a suitable chassis. (It is not actually an Interceptor frame but a late twin — looks the same, but the frame number gives the game away.)

"At this time no attempt had been made to get her running and I nearly parted company with it when the National Motorcycle Museum were after a Series II Interceptor. At the time, I had the 800 and also the very first Series II (engine number and frame number 1000 first registered to the Enfield factory October 27, 1967) and one had to go — and they chose No. 1000.

"It was not for another 10 years before it was actually attempted to get it running. This brings us up to 2013 and during the summer had her running for the first time. It has only covered a few hundred miles since as Hitchcocks Motorcycles takes up all my work and play time.

"From what you read they had a large number of advance orders (Ed: one source says 400 of them) for the 800 but it is immaterial as it was all too late to save the factory.

"Whether it was ready or developed enough, I do not know, but would suggest that there were no extreme changes between this and the already proved 736cc. It would not have needed too much proving.

"We have talked about reproducing a twin engine for many many years. The heart says make it the Series II, the business approach calls for the earlier engine as it will breathe some fresh air into the parts availability for the 500/700/736 twins. But we are a long way off this as it requires a massive investment in both time and money."

Started in Redditch, England, the ancestral home of Royal Enfield, in 1984, Hitchcocks has grown into the key supplier of parts for the English made Royal Enfields as well as for Royal Enfields from India. Hitchcocks gathers up old bikes and supplies of parts, sources reproduction parts and even manufactures new and improved parts.

Their catalog and very helpful parts books can be seen online.

Allan wrote:

"Next project will be a Clymer Enfield. I recently picked up a basket case with engine number IB1001X; the factory ledgers have this as a prototype engine sent to Tartorini in Italy. Hopefully this will not take over 20 years to get up and running!"