Hi Baz. Got the flywheel off yesterday, had a right game with it. Think Facebook only allow one photo in a reply to a post, so will send what I have in a succession of replies to illustrate the matters better. Believe the year of manufacture to be 1951 with the H (missing the bottom left leg) after 2A. Do not think the engine has done much work because there is no wear in the bore and what little carbon there was on the piston and head mostly wiped off with a rag. Took the head off, there was no gasket. Do you know if this is correct. I do not think the cowl has ever come off because the bolt threads for the tank straps and carrying handle still had the lime green paint I think Alcon put on at their works. Believe Jap supplied the engine covered in red oxide as it is inside the cowl and some of the cylinder fins. Put a large socket in the bore and replaced the head so the engine was locked. Knocked of the three sections of the roll pin and the pulley undid by hand! Half undid the three set screws on the flywheel so I could get the legs of a side hammer puller underneath. No go, was worried about damaging the threads on the flywheel. Went to see a mate who had 2” long ¼” Whitworth bolts and put these in a four slots attachment I have for the puller. After a lot of effort, it came off and immediately saw the reason why it was on so tight. The surface of the shaft and the hole inside the flywheel seemed to show signs of a seizure, yet the shaft does not rotate inside the hole. I think either there was swarf or similar on/in it during assembly, or a machining flaw and if known, may explain the roll pin. Initial continuity HT test showed a variable reading, think the black probe was not on a good ground. Have tested again yesterday, both HT and LT resistance is OK. Tested the condenser with a Megger, it failed. I do not use tradition condensers anymore, use a modern polyester film 630v 220nF/0.22uF capacitor. Was actually hoping the coil was duff so I could try again making up a single wire energy transfer coil system. Am still going to do it, but will take off the existing coil, make a former for a new coil, put the old one back on and complete the engine overhaul. Will test the spark from the existing system, then fit the internal coil I will have made and the external one. Then test that system to see if there is an improvement. Best wishes, Grahame.
