Laverda 1000, why short circuit the two ignition coils?

[Wup]

My Laverda 1000 (1977) has the square ignition relay with one switch that switches off the power of the HKZ-unit to stop the engine. See figure 1.
Models build after 1977 have an ignition relay with two swithes that short circuit the two ingnition coils to stop the engine. See figure 2.
Why has Laverda decided to implement the relais with two switches?
Applying this relais and wiring is more expensive. So there has to be a good reason.

 

[sfcpiet]

The HKZ is a magneto ignition, it is grounded to switch off. There is no external power supply, it is self-sufficient, ie, as long as the crank spins, power is generated for the HT coils.

The later BTZ is a battery-powered ignition, power supply is cut to switch off.

Both these ignition systems suck.

piet

 

[Wup]

Piet, thx for your answer. However it does not answering my question.
I drove over 50 kKm without probems with the HKZ-system.

 

[Rob]

I understand that the earlier type of stop relay fitted to HKZ systems was unreliable. It isolates the magneto coil to kill the engine so has to cope with high(ish) AC volts compared to the later relay which just shorts the trigger coils - very low volts!

 

[CLEMTOG]

(please God) I hope that I am correct, both those diagrams depict the HKZ system easilly identifiable by the box with three ignition coils/spark plugs,
The BTZ system is enabled by power delivery and disabled by disconection of same, as Piet says, the alternator output went up a few times with the BTZ system as well, good job too, still not realy adequate for even the last ND eries 11 type, but just about, TOG (1200TS) has never realy given me an undercharging problem, just ignition woes, see below
CLEM

I had no end of engine failures on TOG in the 90's due to failed ignition boxes, discovered at the same time, but obviuosly they did not fail at the same time, one box did not advance at all and the other was only advancing about half way, since then all has been good (touch wood), it makes me think that there might have been good boxes and not so good boxes, different batches perhaps, differring internal components?

 

[iis_iis]

There were two types ( possibly 3 ) of stop systems for the HKZ, the disaster of open circuiting the HV exciter self generation coil, AC output. The next one was to short out the pickup reluctor pickup/sense coils, to inhibit engine ignition. Both factory solutions were problematic, in theory if not inadequate items in production. Mechanical engineers do not always sort out electrics overall, Not sure why the op wants the question answered, been covered over the years many the topic. HTH j