Treen 350 cc desmo research-engine


Treen 350 cc desmo research-engine Charles Treen, the son of the designer, was so kind to react on my “Mystery-solving page”. By courtesy of Mr. Treen jr. we can now for the first time reveal the very desmo-system. It is classified as a variant (=incomplete version) of the Group 7C system. Mr. Treen had conceived the objective of 150 b.h.p. per litre at 9.000 rpm from a 350 c.c. (= 53 h.p.) The engine was oversquare (bore x stroke of 78 x 73 mm) and had a vertically split crankcase with a dry sump oil system. With a twin plug ignition and very big valves the hemispherical combustion chamber was fairly complex. The desmodromic valve actuation uses roller cam followers, and a short connecting rod from the cam follower frame to the head of the hollow valves. The work was started early 1956, but because money and time ran out the nearly-completed unit stood for some years untouched by Major Treen. Actually somehow the development work was never started and in 1965 the dust gathering parts were scheduled to go to the Design Laboratory at Queen Mary College in London, where a certain prof. Thring would like to have it. I understand today it is back again in the Treen family (son Charles Treen). Text taken from the B.M.S. article. Spring 2008 the Sammy Miller Museum crew cleaned and exhibit to the public the Treen Desmo in the SMM.

For more info see the magazine article at : and: B.M.S. Bruce Main-Smith, Treen’s Desmodromic Single, Motorcycle Sport, March 1969. p. 106-109.

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[Classification = Group 5]