Take out spark plugs and inspect for fouling and cracks on porcelain, replace if necessary. Check for loose plug leads. Fuel in tank could be old and octane too low.
I think there is a bit of a rebellion going on in some parts to convince Aprilia to take ownership of this problem.
However I'll NEVER knowingly buy Piaggio again.
Shame really, cos I'd buy a v4 in a hearbeat
I love the bike but the problems are rubbish really ...3 stators ...New wire loom and new dash ... first 3 years was no problem ...last 2 years I've had it all go wrong lol