1200 cutting out any suggestions please

S

steve s

Junior member
Location
East yorks
Hi I'm hoping that some one may have experience the problems I'm having
'77 1200 original electrics,
after about 6 miles riding engine cuts out, it will restart but only tick over, leave it to cool it will run OK.
I'm pretty sure it's electrical as it did it once from 50 mph, went dead as if turned off. Within a few mins it would start/ just about tick over, 15 mins later the same, 40mins it ran ok..

Fuel is getting through OK,
I suspect either the emergency relay or the original ignition (silver box)
There's no issues with voltage anywhere that I can see,
I'd like to be sure I've not missed anything before I get a new ignition system fitted. Has anyone had similar problems
Thanks in advance..
Steve
 
Electrics are not my strong suit, but I'd be tempted to start by isolating the emergency switch.
You'll need to put switches in the bypass, or stall the engine to stop it running.
At least it would confirm if that's what's causing the problem.
 
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You wouldn’t be wasting any time or money replacing the ignition system, that’s for sure, although it may not solve your problem.
I’d be checking the wiring for good connections, insulation chafing etc. If nothing obvious then I’d replace the coils, since you say it seems worse when hot.
 
FWIW, may well be electrical, though a 77 would be BTZ if oem, reads in your post Steve as a HKZ? Easy things first, reads to me as a blocked vent in the fuel filler cap. Quick test by filling up fuel tank hitting 100kph as the engine dies, flip up the fuel cap while at 100kph or better, by helmholtz effect the fuel is drawn out of the open tank filler and sprays fuel all over the ( possibly old blokes ) redundant bits, the engine starts to pick up as does the burning sensation on lower body....true, done what seems liked a good idea, at least the cutting out was identified, know some of the lads here have had same issue/mystery. If not fuel starvation, then back to electrical, though the symptoms described appear not usual for electrical. If it is a HKZ then inspecting the multipin connector and clean/lube perhaps is in order. From failing memory there are 3 different types of stop engine for HKZ self generating operation to be controlled, open circuit the pickups ( bad idea to unload generator type coils ) then came short circuit the pickups output, sort of ok until the barrel relay became unreliable, the third eludes me as i type...may be mistaken on a third mode, though does seem in the mind going back 30+ years....

Andy has good advice, though the small HKZ coils are very well made and i have never seen a failed unit, the history of the engine would preclude Red Motoplat coils... though never know with some bikes, Motoplats were well known for random cutting out and then working after cooling down...HTH j
 
Thanks all,
I've already checked the petrol tank, im sure there is no issue with fuel, no vacuum in the tank too.

It's the hkz unit/small coils.

I've had coil issues on other bikes in the past I'm pretty sure they all would not cut out at once ?
I'll have another session on the bike during the week, it's a bit of a challenge but I'm sure its something simple..
I'm not too bad with a multimeter, and have checked for high resistance in various places .. just not in the place where the fault is yet !
The bikes runs and ticks over fine, so next time out I'll need my meter
I also live on the top of a slight hill
It's hard work pushing it home
Thanks again.
 
"If it is a HKZ then inspecting the multipin connector and clean/lube perhaps is in order. From failing memory there are 3 different types of stop engine for HKZ self generating operation to be controlled, open circuit the pickups ( bad idea to unload generator type coils ) then came short circuit the pickups output, sort of ok until the barrel relay became unreliable, the third eludes me as i type."



Thats and interesting comment... "until the barrel relay became unreliable"
it also appears to descibe my bikes workings. I.e. the 'safety' relay shorts 2 generator coils when the ignition is turned off
I'll try the socks suggestion and bypass the relay
Thanks
Sorry I messed the quote up
 
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Ok, fuel issue off the list, as Andy mentioned the condition of wiring and connectors. Easy things first of course, careful look around at accessible items, if you have a magnetic flywheel extractor tool, would look carefully at the exciter coil under the regulator coil on stator plate. Keep in mind the type of fault your working on, could be internal intermittent failure for the exciter coil, have seen that previous, hard to diagnose without a known good replacement. Though a thorough inspection of wiring condition in that area is straight forward. j.
 
As said, try the easy stuff first.
First check for me would be to take a close look at the “chocolate block” connector on to top the frame spine at the back of the tank. Check the wiring connections are tight but often you will find a broken wire that is making intermittent contact.
Check the condition and bonding of the small earth wire that loops from the harness at the HKZ on to the frame.

Those barrel or torpedo relays are notoriously unreliable. I dispense with them and put a normally open relay in the power feed (red wire) from the HKZ ignition coil. Use a high amperage relay, not a Chinese cheapo.

I also had a similar fault that took me a long time to find. It’s worth checking but it’s not likely it is also your problem. I fitted a NOS HKZ lead and had intermittent sparking issues. It turned out that the spade end on the red wire in the push on HKZ connector block was not secure, when I pushed the block on, the wire was pushed back and the female/male spades were not interlocking, simply touching.

HTH
 
Laverdian said:
As said, try the easy stuff first.
First check for me would be to take a close look at the “chocolate block” connector on to top the frame spine at the back of the tank. Check the wiring connections are tight but often you will find a broken wire that is making intermittent contact.
Check the condition and bonding of the small earth wire that loops from the harness at the HKZ on to the frame.

Those barrel or torpedo relays are notoriously unreliable. I dispense with them and put a normally open relay in the power feed (red wire) from the HKZ ignition coil. Use a high amperage relay, not a Chinese cheapo.

I also had a similar fault that took me a long time to find. It’s worth checking but it’s not likely it is also your problem. I fitted a NOS HKZ lead and had intermittent sparking issues. It turned out that the spade end on the red wire in the push on HKZ connector block was not secure, when I pushed the block on, the wire was pushed back and the female/male spades were not interlocking, simply touching.

HTH
Click to expand...
Thanks, I'd already remade all the choc bloc connections, but will check the earth and connections to the control box this week
thats all good advice and appreciated thanks , I've just ordered a new omron relay, may as well fit that whilst I'm at it

Thanks again
 
Some further comments as worthy or worthless as it may evolve. Intermittent faults are best investigated by replication of the known fault condition(s). Most obvious at first is to "check" all the associated mechanical parts. In doing so you may disturb the actual fault or introduce new "faults" that appear as the original fault or most difficult, several faults that appear to be just one fault. Disturbing the original fault can provide remedy for some time, little or long, only to reappear again. More a philosophy fault chasing than an outright technical approach. What i taught in electrical engineering classes, little value in teaching what i know technically as that is all the students would have, rather a developed signature approach for each student based on the situation presented to them, many was the major factory shutdown fault solved while away from the machine, having a wee in the boys room, wry smile here. More than a few here have that insight methodical approach, also need the philosophy to reduce wasted time.

Did some 30 years ago, repair a faulty HKZ module, cut off the face ( like a bread end slice ) dug out the soft potting mixture, located the faulty HV shunt SCR ( shorted ) and replaced it, there are two other SCR's to drive the small ignition coils. The sliced off "face" reinstalled with electrical grade RTV adhesive/sealant and off the owner was going again in Victoria, he rode to work every day, was his only mode of transport. Open circuiting the HV coil is one way of sorting the self generating HKZ mode, have a concern over the short duration unloading of a high turns winding device, ie possible interwinding flash over and possible shorted turns failure. That coil produces around 400Vac at variable frequency related to motor rpm. HTH j
 
Long shot, but worth eliminating... Ignition switch? The soldered connections on the back can fail - but still touch, most of the time).
 
Thanks for the suggestion, there is a relatively new key switch fitted and a low resistance reading from it.
So it doesn't look like it's the culprit.. but who knows
 
steve s said:
Thanks for the suggestion, there is a relatively new key switch fitted and a low resistance reading from it.
So it doesn't look like it's the culprit.. but who knows
Click to expand...
Ignition switch is not directly relevant to HKZ machines cutting out.
If you have swapped out or bypassed the stop relay then as John has indicated, likely that you have a heat related failure of the ignition box or exciter (magneto) coil. I know some folk like the HKZ benefits but IMHO such systems are definitely at the end of their useful life now
 
Some sleep and the mind works best in the mornings, down hill rapidly from then on.... Laverdaian, suggest a better quick rewire of the open circuit control of the exciter coil is to have it shorted to battery negative or the terrible term "earth", when ignition switched +12V is not present. More than likely the actual motor is not at hand, getting close to 50 years since HKZ were installed.

Have a soft spot for the HKZ, always did, unlike the BTZ i call a hoax on many Italian motorcycles. About to fit a HKZ to a triple of rare features ( recessed rubber inlet stubs, lined cam followers, two web cast on crankcase upper etc ). Spring retained impulse cam, be fun....no really, grin.

As Rob indicates best practices first, if heat related fault, time to send the missus out shopping, grab the hairdryer, tank off, alternator cover off, remote fuel tank feed the carbs, start warming up the ignition module, stand a bit of cooking, not evaporate water hot all the same, see if motor starts or run the motor on center stand while heating. Ditto the stator plate. A can of freeze also assists in heat cold cycling for thermal faults, actual location. Also you could move the various sections of the wiring harness and terminations to see if the cutting out can be drawn down upon. Can be rewarding actually finding the fault or faults, it is the prior hard yards and seemingly endless slog locating the issues, the can be unrewarding. Hope i make sense. HTH j
 
BTW, Steve, does the 1200 still have those intermittent open fuse cartridge, oxidized holder contacts? If so their time is up, original factory is great, pushing bikes uphill and being stranded concentrates the mind on what original factory item truely means, in particular electrical equipment. j.
 
Thanks all again for your input, hopefully I'll get a few hours on it tomorrow, I now have a list of things to check.
I've not needed a hair dryer for quite a few years now, but it looks like I'll be getting re acquainted..
Thanks
 
Paul Marx said:
Haggis said:
Long shot, but worth eliminating... Ignition switch? The soldered connections on the back can fail - but still touch, most of the time).
Click to expand...

Not heat sensitive though.
Click to expand...
Bad solder joints are often heat sensitive in a couple of ways.
Thermal expansion/contraction can make or break the circuit.
Also, if moisture and other impurities get in the joint, it can behave very oddly - something like a dodgy semiconductor. In such cases, a change in temperature is likely to change its behaviour.
 
Had a MZ 250/1 which would cut out after about 20 minutes and only re start once it had cooled down - It was the coil .

I would agree the ignition switch wouldn`t come into this - this is the CDI system by the sound if it which is basically a flywheel generator system which when up and running sparks directly to the plugs ( sort of self contained ) .
With this system , before the factory fitted the stop relay which grounds the ignition , anyone who wanted a Laverda triple could simply walk up to one , bump start it and ride off down the road without having to insert a key into the "ignition switch" .
It`s not so much an ignition switch , more of a battery switch , which then powers the starter motor to turn the engine (and generator rotor) over , which is when the ignition side of things starts happening .
With that in mind I would think any fault would lie somewhere between the stator plate coils , up to the ignition box and it`s coils .
It`s also a good idea to disconnect the stop relay as has been suggested to see if that makes any difference as all that does is to basically interfere with the whole thing .

If it was me I don`t think I would bother trying to find out what the problem was , 45 years is a good innings for a ignition system , so just fit a decent replacement like the Witt/DMC and be done with it .
 
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