Socket size for Jap 2A engine.

Hi there just asking can anyone give me the socket size I need to loosen the nut on the rope starter pulley (to remove wico flywheel) I have tried all the sockets that I have but no joy, thank you. (JAP 2A engine approx 1948)

You have a nut on yours. Mines got a big slot in it.
So can't help with socket size sorry.
Andrew

What is the measurement across the flats?

Hi there Woodsman, its difficult to get a measurement across the flats as the nut is recessed in the pulley, however an 11/16 socket s not far off from fitting nut, have sent off today to ebay for a selection of imperial sockets (2nd hand) and hope that when they come it might have a 3/4 socket...................
Thanks

Will be Whitworth I would think.

Hi there mattblack, got the flywheel off today I used an 18mm socket put a chunky lump of rubber (think it was off a clutch cable originally) in the cylinder block and put head back on, the nut came loose without any drama.
Replaced the ht cable, the old one was in a pretty useless state, gave everything a clean including points put it all back together and we are getting a spark..........so next job is to look at the carburetttor which has a stuck flap in the carb from the governor linkage mechanism, it has a had a good squirt of wd40........
so all good so far !.

Another problem area is the spark plug now that really is stuck tight, I was going to leave well alone but the spark plug ceramic top tip broke off.......so I am will have to remove and I am a little fearful of the spark plug snapping off when I try to unscrew, any advice on this would be very helpful. PS have doused the spark plug with wd40.

Plenty of heat cycling with gas gun and Plus Gas or other Penetrating fluid. 
Kano AeroKroil is good but a tad pricey. Screwfix own brand is cheap and seems OK.  (WD-40 is Water Displacing lubricant) 
Take a few days over it - there's no rush!  My local mower repair shop sheared off a spark plug in my first Villiers. I had assumed they knew what they were doing!!

In the end I shoved a Junior hacksaw blade down the middle and carefully cut it in half.

Put a smear of copper grease on the threads of the new one when you fit it, esp. if the head is alloy.

If you can heat the remains of the plug it will expand compressing any corrosion so when it cools there is less preventing the plug coming out.

Alan