The pic can do anything you like, but this is just a concept drawing.
The ocsilate frequentie must be more then the max-rpm you wish, I think dubbled or trippled.
I've found also problems with the BT151, sometimes the cdi sparks without a puls from the hall.
It's very critical how to build the flybacktransformer, you blow within 1 sec the transistor and the scr.