3C Kill Switch Relay

T

treoleileagh

Full member
Location
Australia
Trying to track down the reason a 1976 3C (old HKZ ignition) won't light up. The manual shows a kill switch relay connected to the alternator output loom at the connector block beneath the fuel tank.
The relay appears to be missing on this bike.
Can anyone tell me what it looks like and where to hunt for it. Are they still available or is there a satisfactory work around?
Thanks
 
Two types of kill relay were used. Early bikes had a silver coloured rectangular shaped one. No idea where it was located (green book says it was rubber mounted) but should be easy to trace via the red magneto feed wire from the alternator housing to the choc strip behind the fuel tank and on from there. It open circuited the magneto coil output and was prone to shorting out which stops forward movement! All before my time...
Later relays open circuited the trigger coil outputs. It's a black tubular thing which should be hanging loose from the wiring loom under the tank above the carbs. If it's strapped up tight vibration can upset it.

If yours is defo 1976 then the green book says it originally had the square relay. Apparently it was common to replace it with the more reliable later arrangement.

Once you've located the relay, you could bypass it to see if it is the problem... just think about how to stall the motor to if it does start!!

Any HKZ system is now beyond the end of its working life IMHO. Wiring insulation from the trigger coils breaks down and similarly component failure in the HKZ box itself. No battery involvement so it's completely independent in operation (apart from the damn stop relay!)
 
Rob said:
Two types of kill relay were used. Early bikes had a silver coloured rectangular shaped one. No idea where it was located (green book says it was rubber mounted) but should be easy to trace via the red magneto feed wire from the alternator housing to the choc strip behind the fuel tank and on from there. It open circuited the magneto coil output and was prone to shorting out which stops forward movement! All before my time...
Later relays open circuited the trigger coil outputs. It's a black tubular thing which should be hanging loose from the wiring loom under the tank above the carbs. If it's strapped up tight vibration can upset it.

If yours is defo 1976 then the green book says it originally had the square relay. Apparently it was common to replace it with the more reliable later arrangement.

Once you've located the relay, you could bypass it to see if it is the problem... just think about how to stall the motor to if it does start!!

Any HKZ system is now beyond the end of its working life IMHO. Wiring insulation from the trigger coils breaks down and similarly component failure in the HKZ box itself. No battery involvement so it's completely independent in operation (apart from the damn stop relay!)
Click to expand...
Thanks Rob, that's really helpful info. Yes this has the long cylinder hanging free. I wondered what that could be. I 'm trying to get it going for a mate and it's my first HKZ encounter. The bikes been in original owner storage for hundreds of years, since turning 46,000km. Not really high mileage.

So if I understand, the bike will start without the kill switch connected, but will not stop by turning the key switch to off position? Hmmm? I guess if the relay is knackered the bike will still start but not stop... same scenario?

I don't know yet it the kill switch works. It was the subject of some serious wiring loom surgery - i've now put that back to wiring diagram correct.

However, I still haven't got warning lights. I'm expecting they will work independently of whether kill switch works, even if it is removed. Am I correct? Not like BTZ where the kill switch isolates everything?

Since it isn't my bike I don't want to change anything, just want to get it started if that's possible.

Once more, thanks for that info
Cheers
 
treoleileagh said:
However, I still haven't got warning lights. I'm expecting they will work independently of whether kill switch works, even if it is removed. Am I correct? Not like BTZ where the kill switch isolates everything?
Click to expand...
The only "warning lights" are the neutral (green), Indicator (amber) and main beam.
There are neither oil or generator "warning lights". No need on a low pressure/high volume oil system or a voltage wild, rectified alternator.
Thinking of which, if it's on the original system, get a "wet", lead acid battery. That system kills AGM, Gel and Oddyssey batteries.
 
treoleileagh said:
So if I understand, the bike will start without the kill switch connected,
Click to expand...
That depends on whether you disconnect and isolate the kill switch relay trigger coil connections (i.e. the two pairs of wires - black & white respectively). Probably easiest to disconnect them at the choc strip (but only after confirming which ones run to the relay, not the HKZ box which are the same colour!)

treoleileagh said:
I guess if the relay is knackered the bike will still start but not stop...
Click to expand...
No. The relay coil is energised with 12v when ignition and handlebar kill switch are 'on'. This lifts the short off the trigger wires.

You can check the AC 'magneto' coil is working by measuring AC volts on the red output wire when cranking - should be 30v or more.

It's difficult to check trigger coils are pulsing without sensitive test gear - probably a static resistance check is as much as you can do. Both should measure the same (~60ohm from poor memory) and be clear of earth.

HKZ box can only really be checked by substitution with a known good one.
 
The Sock said:
The only "warning lights" are the neutral (green), Indicator (amber) and main beam.
There are neither oil or generator "warning lights". No need on a low pressure/high volume oil system or a voltage wild, rectified alternator.
Thinking of which, if it's on the original system, get a "wet", lead acid battery. That system kills AGM, Gel and Oddyssey batteries.
Click to expand...
This bike has ND instruments with a red ignition warning light in the tacho face. Is it a non-functional carry over from a generic instrument design? Thanks for the battery advice. Do these things blow headlight bulbs from voltage spikes too?
Would it be a practical upgrade to fit a BTZ rectifier regulator?
 
treoleileagh said:
This bike has ND instruments with a red ignition warning light in the tacho face. Is it a non-functional carry over from a generic instrument design?
Click to expand...
Yes.
treoleileagh said:
Thanks for the battery advice. Do these things blow headlight bulbs from voltage spikes too?
Click to expand...
No.
I've never seen the voltage go over 18V and, in 49 years with mine, never had any bulb blowing problems.
treoleileagh said:
Would it be a practical upgrade to fit a BTZ rectifier regulator?
Click to expand...
Yes, but, if going down that road, probably worth fitting the Redax uprated (twice the wattage) charging/ignition system.
The output of the original system struggles to allow use of daytime headlights, unless the motor is kept spinning above 4,000 RPM.
On the upside with the old system, the motor bump starts and runs even if the battery is flat or, indeed, removed.
The modern system does not.
 
Thanks Rob, Thanks Sock. So I've found the relay and made a new loom to connect it with the connector block behind the tank. So far so good. The relay has two white wires and two black ones leading out of it, (as well as a yellow earth and blue to the switch). There are 4 alternative ways to connect the two blacks and the two whites (the two whites go to a white from the alternator and a white/black from the alternator, for example.) Since the white relay wires are not numbered, does it matter which way round I connect them? Ditto for the two blacks? I'm not sure I can trial end error through this before knowing the relay is good.
Sock, are you still running the original HKZ system?
 
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