1977 KZ1000 Restomod

calum wrote:

Godd idea. I'll grab a decent multimeter from work and check the current - my multimeter is garbage. Need to double check the coil resistance as well.

word of warning, most Multimeters have a 10amp internal fuse (which in may cases is a pain to get to and an obscure size) and I suspect 2 coils and the Dyna are probably above that

Yeah that's why I need the one from work. Accuracy is an added bonus.

Mmm... maybe I'm missing something, but thinking about it there shouldn't actually be any current flowing. The coils are connected to the dyna S but there is no contact to ground from the green and black wires of the ignition. I did check this without power to the unit though - are the green and black wires grounded when the unit has power and the rotor is missing? 

Side note: How does the dyna S actually work? I always assumed the voltage induced by the movement of the magnet passed the pick-up coils caused the firing and if there was no movement the voltage on the green and black wires was the same as battery positive (meaning no voltage drop on the coils and no current).Guess I need to read up...

Have just found this post from Lou:
kzrider.com/forum/4-electrical/615133-te...-off-the-bike#840673

So it looks like the green and black wires are grounded when there is no magnet nearby. I didn't realise the dyna uses hall sensors and not pick-up coils - probably should have been obvious...
This fits with what I read in the dyna test instructions. The only question left is how quick am I supposed to get the bike started? Lou said in his post not to leave the coils connected for more than a few seconds - that seems a bit extreme but the B-Box did switch off after about 10 seconds the first time. his kind of makes me wonder if 5 Ohm coils would be a better option...

Do a wierd george relay mod plus extra fuse to feed the dyna ignition. 

 

Thanks, that would bypass the B-Box. But I'd still have to make sure I didn't leave the ignition on for any length of time without the bike running, wouldn't I?

The ACCENT ignition has a ignition coil "auto off" feature in the eletronic circuit board.

z-fever.de/shop/de/product_info.php?info...raftversteller-.html

 

That might be the way to go, thanks.

Feeding only one relay coil generate less current load as feeding two ignition coils plus electronics.

You can also use a Bosch fuel pump relay that close and hold the switched circuit only if a rpm or coil signal is feeded to the relay, like the MK 1 Golf/Rabbit GTI it does.

 

calum wrote:

Have just found this post from Lou:
kzrider.com/forum/4-electrical/615133-te...-off-the-bike#840673

So it looks like the green and black wires are grounded when there is no magnet nearby. I didn't realise the dyna uses hall sensors and not pick-up coils - probably should have been obvious...
This fits with what I read in the dyna test instructions. The only question left is how quick am I supposed to get the bike started? Lou said in his post not to leave the coils connected for more than a few seconds - that seems a bit extreme but the B-Box did switch off after about 10 seconds the first time. his kind of makes me wonder if 5 Ohm coils would be a better option...

Much like points ign the coils need to be grounded to energise, it is when you break the ground (points open, trigger pulse) that the magnetic field collapses and the HT voltage is induced in the secondary winding - is the coil feed not controlled by the kill switch as it would be with a wired George by-pass relay? Powering the coils for more than a few minutes does risk damage. I suspect the initial drop out delay was because the current flow is close to the circuit trip point. 12amps through a 10amp fuse takes a little while to blow as the heat needs to build up
I agree with Scirocco ref the by-pass relay. Not sure about the fuel pump relay as the the cranking speed may not be high enough on cold start, however another option if you don't use the kill switch would be to switch the by-pass relay ground through the oil pressure switch, that way the coils would only be powered when the oil light goes out ( bonus is if you loose oil pressure the ign will cut and maybe save your motor)

Thanks guys. 
Using the relay will save the B-Box, but the draw on the battery and the current through the coils and ignition will stay the same. The fuel pump relay won't work with my tach signal as it comes off the coils - no power to the coils, no tach signal and then no power to the coils... catch 22. It may work off the oil pressure switch but I think I'd probably just go for the accent ignition with the built-in safeguard.
I do have a kill switch, but the speed at which the B-Box fuse blows makes me weary of having the ignition on for more than a couple of seconds before starting - I don't want to fry the coils/ignition just because I got distracted. I need to test the coil resistance and the voltage drop to the ignition. If the B-Box fuse is 10A and the lights (run through a relay) draw about 150-200mA then the fuse shouldn't be blowing (should be max 4.5A through each coil - assuming 14V and 3 Ohms).

Will test the coils later and report back.

EDIT: Just got a reply from Axel - the B-Box ignition output blows at 5A. That explains everything. The Accent ignition is probably still a good idea but I definitely need a relay