[alantf]

Six days later, & it's done it again. The bike had been standing overnight, in the garage, for 22 hours. Temperature - tee shirt comfortable. Tried to start it, starter whirred perfectly, but it wouldn't fire. First thing I did was to get a flashlamp & inspect everything VERY carefully. The end of the overflow pipe hadn't the slightest trace of moisture, nor did it smell at all of petrol. There was no sight nor smell of petrol ANYWHERE. Can anyone explain the vacuum system to me? From the petcock, the vacuum pipe seems to go for a couple of inches to a tee. One side of the tee goes to the front of the carb, where it joins to the engine, & the other side of the tee goes to a gadget on the frame (in front of the engine, & next to the horn) It fits onto a curved pipe on this gadget, & while not really loose, I was able to push it on about 3/8" to the end. Should this be dead tight i.e. clamped? Incidentally, what is this gadget for? I've never seen anything like it before. It seems to have two large diameter pipes on it - one goes to the bottom/front of the engine, & the other vanishes up under the tank somewhere.
Anyway, after the inspection, tried to start again, with the same zero results. Switched to prime, waited around 15 seconds, switched to run, & it started up immediately. No further problems, bike running perfectly, & this time no smell of petrol when I came back to the bike after I came out of the supermarket. Incidentally, before I parked up yesterday, I'd just come back from a 25 mile run.