FZeller,


From the [link=http://www.osengines.com/parts/discontinued.html#carb]#4BK carburettor[/link], your engine is probably the OS.45FSR (unless this carburettor was fitted onto a different OS engine...). See photo from the OS TimeLine below.

This engine is one of the best ever made by OS and is much better than its newer siblings, its replacement, the .45SF and the later .46FX and .46AX.

This engine will also last longer, uses the same bearings (front R-6Z, rear 6902) and if it is the ringed version, Frank Bowman will supply a new ring, if you ever need one. If this is the ABN vesion, ABC parts from equivalent Sanye engines (Magnum, ASP,...) may suit as replacements.

Alan is right about recommending the #8 glow-plug, but you can also use any other long reach 'warm', or 'medium' rated plug, like the Novarossi C-6S, the Enya #4, the Rossi R4, the K&B-1L, or even the OS #8 clone trom Tower, the TowerPower plug.