Mystery 500

[MRD]

Hi everyone
Over the weekend I was talking to a highly respected Douglas enthusiast, about an engine which looked very similar to a 2 3/4 hp but had a capacity of 500cc.
I do seem to remember an engine like this but for the life of me I can't find a picture of it.
Would it be possible if anybody could supply pictures of this machine. All I can remember is that the engine looks the same as a 2 3/4hp, with the tappets/ Valves at the same angle as the smaller engine. I think it was from the early 20's.
Regards   Martin 

[MRD]

Hi everyone
Would my previous post on this be about the Williamson, which was built by Douglas. If so I would still be interested in any information or pictures.
It's one of those things that play on your mind, I've looked through the books I have and tried the internet even trying different search engines to no avail.
Any help would be appreciated
Regards           Martin

[Nick MW]

Hello Martin,

I had a look online and found this (attached) picture on the VintageBike.co.uk site. Nothing else, just the picture, hope this helps.

Best regards, Nick



Photo courtesy of Vintagebike.co.uk

[graeme]

The Williamson engine was made by Douglas, but is much bigger than 500cc - I think 1000cc from memory.

[Dirt Track]

G'day all
I wonder if we could be talking about.....Brough flat twin....ABC flat twin.....Coventry Victor flat twin......Humber flat twin.......Zenith (Bradshaw) flat twin.......Raleigh flat twin......or even one of the Continental makes. Could be a lot of possibilities for this 500cc flat twin.
Howard.