Just been trawling this section, and noticed a couple of entries entitled 'Prototypes'.
Thought folks might like to see this prototype (which is still a project, albeit progressing slowly).
It was constructed in 1912, one of a very small batch (possibly only 2), and contained Enfield's FIRST engine of their own manufacture.
Bert Colver rode a similar machine at Brooklands, and appears on the inside front cover of Peter Hartley's 1980s book, The Story of Royal Enfield Motorcycles. Unfortunately, my machine is not Bert's (note the different steering head angle), but carries engine no.
2, so maybe Bert's was no. 1? The bike has an overhead inlet, side exhaust valve layout, with aluminium pistons, roller bearings throughout, high mounted magneto, and lead loaded flywheels for extra torque. Enfield 2 speed gear, and what I believe to be a prototype rear hub cush drive with screw on cush drum.
If old stuff like this interests you, try a visit to
http://vinvetmotorcycle.simplesite.com/432420583 where I'm recording the rebuild process, along with other Enfield stuff (1912 model 160, 1937 KX and 1957 500 Bullet - last one owned for 43 years). Warning: non Enfield content on there also!