B34-2 Spark Plug -1934

[Barry H]

I have a B34-2 BSA 250 OHV

I'm trying to identify the best spark plug to use

[Y13 Alan G]

Hi Barry. I have several pre-war BSA's all of which use 18mm short reach plugs. In the side valves I use NGK A6 plugs and in the OHV's I use NGK A7 plugs which take the higher compression. I have used these plugs for donkeys years with no problems. Hope this helps.