Rephase and TCI ignition system.

[MacMcMacmac]

Is there any reason I could not install a second pickup for the coils spaced 90 or 83 degrees (depending on 270 or 277 rephase) before the stock ignition pickup to operate a second coil for the right cylinder with an electronic ignition on an 83 Heritage Special motor? Seems to me that you could layout the location pretty accurately with a protractor to get the timing right. Considering the cam chain induced timing variation on points equipped bikes, that might not need thou-perfect accuracy anyway.

Is there a dwell issue? Could I go even cheaper and still use one coil with a wasted spark?

 

[XSLeo]

In theory It sounds doable, not so sure in practice. I guess you can try. Report back with the results.
Leo

 

[mrriggs]

With two pickups, two TCI boxes, and two single output coils, I don't see why it wouldn't work.

I don't think two pickups with one box and dual output coil would work. The uneven signal would likely screw up the dwell and advance.

 

[Street Tracker]

How is each tic going to know which pickup it is assigned? Or will each side just be firing twice and hopefully at a time when it does not cause an issue?

 

[I am Carbon]

How is each tic going to know which pickup it is assigned? Or will each side just be firing twice and hopefully at a time when it does not cause an issue?

I don't think you could assign one magnet to one pickup unit.
"Or will each side just be firing twice"
I'm sure this is more likely each fifing twice.

 

[Street Tracker]

I don't think you could assign one magnet to one pickup unit.
"Or will each side just be firing twice"
I'm sure this is more likely each fifing twice.

I have not given the timing of events a extensive thought but others have and there must be an issue as all rephases I have seen are two ignitions. i am sure if Hugh could have value engineered the rephase this is the first dollar saver he would have looked at Im thinking.

 

[mrriggs]

I have not given the timing of events a extensive thought but others have and there must be an issue as all rephases I have seen are two ignitions.

It's possible to do a waste spark ignition on re-phased motors, you just can't do it with a TCI and crank trigger.

 

[MacMcMacmac]

Ok, I see the problem now. The TCI sees each signal as a complete rotation of the crank and uses this to apply the proper spark advance based on rpm. If it is getting two signals within 90 degrees, then nothing for 270 degrees, it's going to think the motor speed is changing wildly. Too bad. No way I'm putting another TCI on my bike, kinda defeats the whole keep it simple ethic.