SIP VAPE IGNITION DC For Lambretta

Good Afternoon people, hopefully some one can advise, a very good friend of mine is having problems trying to set up ignition timing for the above Vape, telling me that he thinks it may have to elongate the slots on the stator...is this right ??? also....whats the best setting on the timing as we re used to 17 or 19 Deg....Hope  someone can advise and if possible....anyone with a wiring chart for DC so that I can see what he means.....Thanks People