I have struggled for the last two years to find a plug spanner that fits my Triumphs properly. When I asked my local dealer technician, he showed me his cut-down Snap-On 1/2″ square drive socket.

Problem (1)
Most (all?) deep plug sockets measure 24mm outside diameter which is too big to fit right down into the Triumph cylinder head. I have been using the plug spanner from my 1972 Honda 500/4 but decided to try and get a “proper” solution as the old spanner is barely long enough.

Problem (2)
I hate bi-hex sockets.

Problem (3)
Snap-On socket retails at over £25!

Solution:
I should know this by now. The best place for this sort of problem is your local “everything from broom-sticks to lightbulbs” hardware store and there just happens to be one in Wokingham (“Wokingham Decor” – they deserve a plug)
The guys in there went through all their catalogues and phoned various wholesalers and manufacturers and found me a Teng socket that fitted the bill. It’s a single-hex. The stock number is M120042-C “1/2 inch Dr 18mm Spark Plug Skt”

Next to the neighbour with the lathe. Basil restores old Matchless AJS motorcycles and is good at this stuff. He cut the socket down to 23mm O/D.

I haven’t tried it yet (do you know what the temperature is in my garage right now?) but will let you know how I get on.

And here’s the manufacturer’s tag: