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Curtis Racing Frames - Custom Street Machines

This series of shots shows one of the custom street machines made by Curtis Racing Frames in 1974/5. It is a Vincent engine special. Being a Vincent enthusiast, it was logical that I wanted to improve on the racing Vincent I used in the 60's, and build a sport bike for the street.

Vincent Street frame by Denis Curtis

These photos supplied by the owner Mr. Jim Brokensha of Vancouver Canada

HRD Vincent

Curtis frame HRD Vincent

Vincent HRD with custom frame

Norton Gearbox and transmission and Rickman Style gas tank on this Vincent

Vesco style seat and honda wheels, brakes on the Curtis frame HRD Vincent

Curtis Vincent custom motorcycle

HRD Vincent

This bike featured a tubular backbone frame, Norton gearbox/transmission, Rickman-style gas tank, Vesco style seat, Honda wheels and brakes and Dunlop tires. A very special oil tank was made up to clear the rear carburetor of the v-twin engine and the fairing and screen was a Dunstall Mark II replica. The owner had modified the engine extensively for performance. This bike is now owned by Jay Leno. See ARTICLES Page.

Curtis Vincent The HRD on the tank are the initials of the original designer of the Vincent motorcycle, Howard R. Davies. When Mr. Davies' company failed in the 1930s Philip Vincent took it over and developed the V-twin idea further. Vincents went out of production in 1955. The Vincent Owners' Club, based in the UK has recently completed the re-manufacture of all of the component parts for those motorcycles through its VOC Spares Company Ltd.

mono-shock Honda 750 SOHC 4-cyl. frame kits
See ARTICLES Page for the full story.

Piper UK Honda K1 cylinder head with 4 valves per cylinder.
We were asked to build some mono-shock Honda 750 SOHC 4-cyl. frame kits for a customer in Ontario. The frame was designed to accept the Yamaha TZ mono-shock unit. Four of these frame kits were built – 2 were supplied to Ontario, one to Winnipeg and the other to a Vancouver customer. The Vancouver customer built his into a street bike using a much modified 750 Honda engine. This article describes the trouble this customer went to, using a Piper UK Honda K1 cylinder head with 4 valves per cylinder.

We have since learned that one of the 750 frames sold in Ontario was recently found with a 550 Honda 4-cylinder engine replacing the original. It had been successfully raced in Ontario in the 80's and 90's.

Next: Road Racers

If you have any information or pictures of Curtis Racing Frames from the period please Contact Us. We would really like to feature as many frames and frame modifications from that period as we can here.

Curtis Racing Frames; a sticker from 1970's

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