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British Motorcycles

Dalm Motorcycles and Engines

J. C. Dalman and Sons of Birmingham produced a motorcycle in 1914 and 1915.

The make was very short-lived and was a lightweight two-stroke machine typical of the era.

Although the motorcycle itself soon disappeared, the Dalm 318cc engine with bore/stroke of 73x76mm remained available as a proprietary unit until well into the next decade.

Marques which employed these engines included:

  • Aurora
    Grose-Spur
    Hansan
    J.N.U. (1920)
    Kelly
    Maxim
    Neal-Dalm
    Nickson
    P & S
    Supremoco
    Symplex
    Wheatcroft
    Venus
    Weatherell

THE DALM TWO-STROKE.

AMONG the most interesting of the medium-powered air-cooled two-stroke engines the Dalm engine takes a high place. It is designed and manufactured throughout by J. C. Dalman and Sons, of River Street, Birmingham, and not the least wonderful point about it is the fact that no material alteration has been made to the original design. The cylinder has a bore and stroke of 73 x 76 mm., giving a capacity of 318 c.c. The transfer pipe is cast with the cylinder, and one of the first points to strike the eye is the great area of the exhaust ports, which discharge the gas into two separate pipes each of lin. full inside diameter. The transfer ports also are of interest, for though the gas enters the duct by two large ports it is distributed over the face of the baffle by four smaller ones. A release valve placed in front of the cylinder is arranged so that the gas is led directly into the exhaust box casting thus helping largely towards the ideal of a clean engine. The piston is domed somewhat less than is the case with the average two-stroke, but the baffle is extended somewhat above the dome so as to prevent loss of gas through the exhaust port.

It is interesting to note that both crank bearings and big end bearings are lined with white metal instead of the more usual phosphor bronze, and the large surface in conjunction with carefully ground crankshaft gives excellent wearing qualities. The balance weights are carefully machined and riveted to crank webs. The "petroil" system lubrication is employed, the surplus passing through ducts to the crank bearing.

We were enabled to see an engine on a test bench, and it was interesting to note it started up by the simple expedient passing a rope round the belt pulley giving a sharp pull. The engine ran evenly and emitted a clear clean exhaust The compression was excellent in spite the newness of the engine - a feat which is partly due to soundness of workmanship, and partly to the fact that three piston rings are employed.

The Motor Cycle, November 26th, 1914. p592


Sources: Graces Guide, The Motor Cycle, et al.



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