83cc BBK A9 cam problem

[UU4444]

Hi everyone,

I'm new to this group all the way from Australia, I have an issue I hope someone can shed some light on.
I have just fitted a 83 cc BBK and big valve head to QMA139 scooter. When fitting the A9 cam I struck a problem with the inlet valve hitting the Piston once the valve lash was set when trying to wind over by hand. I was confident valve timing was correct, I have put standard cam back in with no problems. Has anyone encounter this problem before?
The engine runs well but has very minimal power increase, I would think using the standard cam is to blame.

Thanks UU4444