-JdK- I had this bike since 2007. Bought from Mark Upham in Austria who got it from someone in the UK. I sold it in July 2018 to Russ in the UK. It's a 1929 Model 18 modified for vintage racing. Correct for 1929 are frame, engine, gearbox, rearwheel, oiltank. The petroltank is probably from a CS1. The front hub is probably Webb and is a much better brake than the original. Girders are very desirable paralel Norton International.
The bike has been used for amateur racing in the past. Click this link for pics made around 50 years back. The engine has been tuned by an expert, most probably Stan Johnson. The flywheels have been polished and skimmed and run extremely smooth. It has a slipper piston and larger size inlet valve. The cams are probably remodeled or IT racing cams. It runs on Castrol R40. It comes with a small devise that blocks first gear, essentially turning it into a positive stop for 2nd and 3rd gear only.
Simon remembers the bike from the past: "I am pretty sure this bike is one put together by the Lewis Bros back in the late sixties or thereabouts for racing purposes and they even lent it to me at one Crystal Palace event when the New Imp I was down to ride misbehaved. The engine fitted at the time was one of Stan Johnson's and had plenty of urge but I thought the steering was awful as the fork dampers were done up too tight. No time to discover this as I did not practise on the bike before the actual event. If I recall correctly it has the little plunger device fitted to help with gear changes (not missing second gear) and it also had a CS1 tank fitted which needed extra height rubbers to clear the top frame tube."
The bike went very well. Click the video above to see it running. Gearing is long, it needs clutch slip for takeoff but very pleasant once on the go. 2nd gear can be used till 80 km/h. It has been clocked using satnav at 120 real km/h and is faster than many end-1930s 500cc bikes.