High cam production racers

In the earliest days of Hicam production a "Competizione" version was available from around 1954. Odd looking with Earles forks & small wheels (18" front ,17" rear) these bikes are now extremely rare. Capable of around 90mph in race trim they were provided with full lighting equipment. Most of these bikes carried engine & frame numbers (usually identical) in the 500xxx series.

The first version was soon followed by a more conventional looking model which more closely resembled the road bikes. This bike had a telescopic fork with conventional 19" wheel sizes. Whilst looking very similar to the Turismo.many parts are unique to the model such as the large fuel tank which is cut away on the underside to clear the cylinder head & allow a lower mounting to be employed thus allowing a racing crouch for the "pilota". Again a 500xxx number was used for frame & engine 

The next series of production racer, or MSDS as they were known in Europe (Machina Sport Derivata dalla Serie) used a very similar frame to the previous model but with different tank & seat units. In this picture the signature massive cigar silencer can be seen & the optional "D" shaped rev counter ( a converted Smiths speedometer) can just be seen on the fork top yoke. Most of these bikes were 501xxx series numbers.

The final version of the MSDS had a different frame, tank, seat & toolboxes from the earlier models & some pix of the bikes show a version with no silencer or speedometer evident. Some would say the most handsome version of all these bikes are not quite as hard to find as the earlier types...or should I say not impossible to find. These versions usually carry the 501xxx series number. 

The standard 500/501xxx series were equipped with chain driven cams (see Camdrives) but some were fitted with all gear drive systems. Hard to tell from the outside. 

In the UK a series of 170xxx machines exist with gear cam drive, CR gearbox & X1 cam. As yet I don't know a lot about this series other than 3 bikes exist in the UK & an engine is known of in Italy...any ideas?