My bike had this problem a few times last year but this month it became much worse. Sometimes, lets say 2 out of 10 times it will die when i put it in neutral or when i hold the clutch. The more troublesome fact is that it will also happen while riding... let's say i'm driving 50km/h and i will shift from 4th gear into 3rd. The moment i let go of the clutch and start to add a bit of throttle it dies.

Or sometimes when in neutral and if i add just a little bit of throttle really fast it dies aswell.

Sorry for weird english
Anyway, any idea whats wrong? All help appriciated.