Well, made what feels like progress. This eternal conundrum - is it electrics or is it carburation?
Obviously, having just fitted a new carb, I'm concentrating attention on the mixture. But the bike runs for a few seconds up to maybe half a minute then it quits and feels like a misfire. Plug wet and black.
Yesterday, decided to go through the ignition system
again. Check my timing marks, check when the points open. Off with the primary cover, collect the ATF, use my homemade TDC tool. Yup, my pen marks are still visible and they are correct. Turn the engine with a 1" socket on the alternator and using a test light, confirm that the points open 10° btdc. For the first time, use my advance-lock tool - you move the points to full advance, screw the tool on and it holds that position. At full advance, the light comes on at the 32° mark.
So far so good. While I was in there, decided to refit the original condenser and points - they meet up better.
The power feed to the points uses a little clip and the wire was looking frayed, altogether a bit sorry for itself. Took it apart and this happened:
Sorry about the out of focus picture. That wire next to the pen is the points power feed and the little clip just fell off as I undid it.
I think a dodgy connection to the points might account for the engine quitting.
Have made up a new wire, able to re-use the little clip - opened it up, cleaned it off, folded it over the end of the new cable and soldered it good. All back together, started the engine. It started easily, ran for a minute or so, then coughed and spluttered a few times and died.
But I feel I have eliminated an electrical problem which was causing, uhm, a problem. Ran out of time, but feel that I'm going to be able to work through setting up the carb without having a pesky electrical gremlin confusing the issue.
Onwards and upwards. Been a few days since it felt like that . . .