A couple days ago, I shut down the bike and went inside for a second. When I returned there was a pretty good size puddle of gas under the bike. I shut the petcock off and, of course, it stopped. I had a friend come over and he took it off and apart and back on and it was cool. I went for a ride last night and it was good but after my ride today the leak was back.
I added a video to show how fast the leak is from dry drip.
This can be solved by grinding your float needle on it's seat using a little valve grinding paste. I have done it and can leave the petrol tap open for a long time with out any leaks.
I think i would prefer/recommend something like BRASSO or car body polishing compound (T Cut) than grinding paste - its too easy to take too much off and make things worse, by leaving a step.
To be honest all these old 276 Amals seem on the verge of flooding - the best money i ever spent was to have an old watch maker re-machine a few float-needle rods for me.
Or even better buy a new one ?