Quite a few people here are using H D stuff. The ignition has a hall effect trigger that senses the gap in a rotating cup. On starting it uses the closing of the gap to fire the system and once a few hundred RPM is reached it then uses the opening of the gap, and advances or retards from there depending on engine speed. Obviously the width of the gap must be maintained when a new cup for a 50 deg twin replaces the one for a 45 deg twin. It also uses two different advance curves, triggered by a Vacuum operated electric switch. The switch is adjustable as to when it switches on what vacuum. One can also buy black boxes that are programable on a computer and one can set such things as a certain number of revolutions before it fires (for use with delicate electric starters, or to really annoy those with a kick starter!), at what rpm the nitrous sytem gets armed, and deployed, even vary from one cylinder to another in case your cases are machined at 51 degrees -)), and my favourite feature; when an engine accelerates hard there is a small lag as the sensor reads the rpm that has occurred, and not the one that is about to occur, and you can program an slight extra acceleration in the ignition to compensate for this!
When cruising along at 70 mph it runs quite a big advance - depending where the initial setup is made, in the order of 45-50 dgrees. When sufficient throttle is given, the vacuum switch operates and a more conservative curve takes over.
Spare parts in almost every major town in the world, and really bullet proof. I put thi setup in more than 10 years ago, and have not touched it since. I changed plugs before I went to Australia, not because they looked bad but because I couldn't remember (and didn't write in the book) the last time they were even out of the bike.
Robert
When cruising along at 70 mph it runs quite a big advance - depending where the initial setup is made, in the order of 45-50 dgrees. When sufficient throttle is given, the vacuum switch operates and a more conservative curve takes over.
Spare parts in almost every major town in the world, and really bullet proof. I put thi setup in more than 10 years ago, and have not touched it since. I changed plugs before I went to Australia, not because they looked bad but because I couldn't remember (and didn't write in the book) the last time they were even out of the bike.
Robert