My 2007 Vespa GTS250ie stalled and would not run about 3 weeks ago. Turns out it was the battery. It would not hold a charge and it had min. cranking power. So replaced it and have been good to go...for about 3 weeks. Now the new battery is doing the same thing. Now, it could be I got a bum battery, but I find that unlikely.
More likely would be the Alternator or Voltage regulator. Is there a simple voltmeter test for these items?