Finally, all the other jobs were done around the house and there were no more show days as the house was sold. I can take the bike out and see what it is like to ride again. The bike had always had a funny tickover where it would sometimes tickover faster. She has Dell Orto PHM 40s so I decided to check Skins' suggestion that there might be some wear grooves from the idle adjusting screws. I stripped the carbs and he was right, so I filed them down and checked all the jets (see previous posting).
Before starting her for the first time I checked the fuel level in the tank and it was quite low. I thought "maybe this leak is worse than it looks, and I need to do something about this". I checked a few other things and noticed that the oil level was high, but thought that I must have overfilled her last time. She started fine but after about 20 seconds she went to around 3,000 revs and wouldn't slow down, so I turned off the key.
During that week I managed to buy a Briggs and Stratton fuel tap from a lawn mower repair shop. I plumbed this in after the fuel pump (between the fuel pump and the Y piece that splits the pipe to go to each carb).
My logic is that although the tap could be under more fuel pressure this side of the pump than if the fuel were to be sucked through it, if the tap is not turned on the pump won't run dry. The tap can also be accessed via the gap between the headlight and the mud guard and it would have been difficult to access it if it had been plumbed in between the tank and the pump.
The needle valves in the carbs are relatively new but I don't think that they are designed to sit for months on end without use, and the fuel pump certainly doesn't stop the flow completely.
As well as preventing the fuel from reaching the carbs when not in use, the fuel tap could be thought of as an anti-theft device, as it can't be seen unless you know where to find it.
In case any one else is interested in doing the same thing, the Briggs and Stratton part number is 698-183 and cost the equivilent of US$14, which was not cheap.
I didn't get a chance to ride the bike that weekend as I intended to balance and set up the carbs, and I ran out of time. This was just as well as when I next had time to do the job I decided that I didn't like the oil level so high. I put a pipe through the filler and was going use it to take out some of the oil.
I checked the first bit of the oil and it smelt of petrol. What had been happening is that the fuel was leaking in to the carb that feeds the front cylinder. When the level got high enough it would dribble down the inlet tract and in to the front cylinder, past the piston rings and in to the sump.
I had to drain the sump and remove the filter. By careful manipulation I managed to get the oil (and fuel ?) out of the oil coolers, then replace the sump plug and filter. I poured the oil / fuel mixture in to a 5 litre can and it filled it completely. I think that there must have been about a litre and a half of fuel in the oil.
Paul