I was having trouble getting my scooter started after it had been sitting a while, and a very helpful comment in my "Scooter Cold Start Struggles" pointed out that the problem may lie with a vacuum petcock in the fuel system which doesn't get sufficient vacuum during start attempts to open.
In this video, I track down the problem, and replace the vacuum petcock with a manual valve system which will hopefully avoid this issue in the future. Many thanks to Steve Randall for the comment on the vacuum petcock.
Here's the link to the Scooter Cold Start video if you're interested: • Scooter Cold Start Struggles