I think the factory spec MK 2 cams are ok for starting, but the Mk 2 cams that Terry sells can make starting very difficult, because the inlet valve closes very late. Try about 85 degrees BTDC too late, ok for a race engine, not street.
Greg,
Yes, I did remember that you had some problems, but the Factory Mk2 does the same, although not to the same extent. When comparing the Factory MK1 and Mk2, the Mk1 makes more cranking or starting pressure than the Mk2, due to the similar late closing of the intake on the Mk2. With the Factory Mk2 (usually no more than 75°) I would not be too concerned about bad starting, but I would be concerned about the cumulative effect of several mods that makes starting difficult...and using a cam that doesn't start as easily as the Mk 1. After all, the Phil's did not feel that the Mk2 was a suitable street cam although most owners today will put up with the problems.
There are programmable ignitions that will deal with the timing retardation issue, but that would take extensive dyno tuning, which is unlikely. The MSD 4217 comes to mind for single cylinders. It can be programmed to start at 4°, for example. I think it will go down to 0°, but it won't go negative for Bill. I think it will hold two timing curves which can be selected with a switch on the handlebars.
Once the Ariel Club gets wind of your tuning skills applied to the Square Four you will be inundated with the bikes.
David