Please help me identify this 1924 Triumph bike

[simonrix]

Hello All,

My brother in law has a 1924 Triumph which I at first though was a model P given it does not have a belt drive of the model H.

The origional purchase paper dated 22nd September 1924, Pretoria, South Africa only states 4hp. The engine number is 43788, the chassis number is 339387.

Nigel has kindly posted a picture here (Thanks Nigel).
  
http://www.vintagebike.co.uk/YaBBAttach/Truimph-modelP-1924-small.jpg
 
I now suspect that the bike may be a model SD but lets see.

regards Simon

[L.A.B.]

A good match?
http://www.vintagebike.co.uk/Bike%20Directories/Triumph%20Bikes/pages/Triumph%20SD.htm

http://www.autogallery.org.ru/k/t/24triSD1cylSV500cc3spd26x3tyres_Yesterdays_nl.jpg

[Sparks]

Hi Simon,it looks like a 499cc SD as you suspected.They were based on the IR Fast Roadster that had four pushrod actuated valves,a central spark plug an aluminium piston,single inlet manifold and two exhaust outlets.  Sparks