I've almost completed my homemade flatshift system, taking inputs from a klicktronic electronic shift actuator. I have a few worries about the ignition cut itself:

All systems seem to break the 12V feed, leaving the neg side intact where the CDI switches it. My worry is, by breaking the feed to the coil i'll effectively collapse the field, inducing a mistimed spark into all 4 cylinders...

I'm hoping the coil is only powered and collapsed during tiny period of spark, which means there won't be a field present when the coil is cut.

Anyone had any experience with this? I don't really want to have to scope the coil output!

I found this which seems to indicate the coil is pulsed on and then off, rather than holding the "on" condition... Good news?



[Edited on 7/7/09 by cloudy]

James,

I think that is right. On the GSXR1100 the 12V is always at the coil (not switched).

I guess you could end up causing an early spark when you cut-out the ignition. I guess switching in a capacitor or resistor instead of open-circuit would bring the 12V down a bit more gently.

What about the same problem when you put the volts back on? I guess it will only do it once per gear change, and not very often even then.

Matt

Is it a CDI (i.e. capacitor discharge ignition) or a conventional electronic inductive system?

If the latter then the coil will only be charged for somewhere between 2ms and 5ms (depending on the coil resistance, inductance and supply voltage) prior to a spark. If you removed the positive feed to the coil during this charging period you would effectively get a weak and advanced spark, the higher the RPM the more advanced it could be potentially. If you were cunning you could design the circuit so it doesn't cut the coil feed if the -ve side of the coil is grounded, which would ensure no early sparks.

If it's the former than it's more complex, since the coil isn't fired by switching off current, but by dumping a big capacitor charged up to a high voltage straight into the coil. This would be more difficult to spark cut, you'd be better off interrupting the trigger to the CDI system in that case.

That's option B, is I just cut the crank sensors (two on the dyna 2000) But without knowing if the ignition would recover instantly it might not be going anywhere, hence following the way the manufacturers have...

I'm not sure how it generates the spark - The website only states "The Dyna 2000 system consists of a state-of-the-art microprocessor controlled ignition module"

James

I would assume a real CDI would have two connections to the coil, or a grounded coil as it fires energy into it. Given mine are perm 12v I assume it's not doing that...
Jaes

hi,

can't you keep the feild going,instead of letting it colapse?
it's only for a short period, so shouldn't be harmfull.

I just need to know the "off" state, I'm going to have to scope the coil ouput...

James

James,

Have you considered using the dyna2000 ignition cut function?

The manual can be found here.

It states:
"safety interlock input -- you can keep your side stand safety switch function or hook up a theft prevention switch, or activate a shift lever kill for road racing"

There is a short paragraph in the manual on this.


Matt

I'd completely forgotten about that!!!

That'll be the way to go!

James