Woodruff key problem

Hello there! I`m the owner of a 64` vespa r, i recently restored it and changed the cylinder to a 130cc one. The problem with it is that the woodruff key from the clutch seems to break to easy, any answers to that? It is the 2nd time in one year when it breaks. Thank you in advance!

Hi there.
Normally it shouldn't do that.
Otherwise the seat of the key might probably be worn out so it has too much play... or maybe you do something wrong when mounting the clutch.
Let someone with much experience assist you and take a look over it.