Only one spark

Nash

Nash

New member
Location
Norwich
Im new on here,in fact I’ve never asked for help on line before.
I have a Mirage 1978. This is the problem.
I want to get it on the road this year but when I push the button I only get a spark on the two outside plugs and nothing on the middle plug.
The strange thing is there is only a single spark on them, then nothing.
I have had to replace a coil on it before.
I don’t mind having to do that again but I just want to be sure that is not the CDI.
Ive had this bike since 1987 and hardly been able to ride it because it has been nothing but trouble.
In fact I spend most of the time hating it but I kinda love it at the same time.
Thanks for any help.
Nash.
 
Not so good Nash, can be frustrating no end at times, electrical issues. All is far from lost, reliability is one of the more prominent features of Laverda, mine always got me home, that is the good news. You are in the home of the enlightened here, providing us with details will, with a small amount of luck and lots of effort, have you seeing your Laverda in a new light, if not spark.... lets see what you can photograph and post here. Hope that helps j.
 
iis_iis said:
Not so good Nash, can be frustrating no end at times, electrical issues. All is far from lost, reliability is one of the more prominent features of Laverda, mine always got me home, that is the good news. You are in the home of the enlightened here, providing us with details will, with a small amount of luck and lots of effort, have you seeing your Laverda in a new light, if not spark.... lets see what you can photograph and post here. Hope that helps j.
Click to expand...
Thanks, photos of what do you think could help?.
 
Well the Bosch ignition is your first problem. Do you have any electrical test equipment such as a multi-meter?

And assuming you get it fixed, the Bosch ignition will never work as good as the modern replacements.
 
Nash said:
Thanks, photos of what do you think could help?.
Click to expand...
The electrical system under the tank, coils and ignition module, we are guessing until a photo helps assess what you have, a 1978 would be, if factory, Bosch BTZ, two separate silver modules. Rather than guess, making certain a best effort. 1200TS is indicating a more beneficial reward for efforts. HTH j
 
John, If I remember correctly, he should see about 300V going to the coil when the CDI triggers it? I have not worked on a Laverda Bosch ignition in many years so am trying to remember what I can. On my triples, three bikes have your ignition and one has the Moto Witt. Your ignitions are still working good after almost 30 years. I cant always say the same about the Moto Witt.

Regards,
Bruce from California
 
1200ts said:
John, If I remember correctly, he should see about 300V going to the coil when the CDI triggers it? I have not worked on a Laverda Bosch ignition in many years so am trying to remember what I can. On my triples, three bikes have your ignition and one has the Moto Witt. Your ignitions are still working good after almost 30 years. I cant always say the same about the Moto Witt.

Regards,
Bruce from California
Click to expand...
Yes Bruce the dump voltage capy to ignition coil primary, is in the 300Vdc range, around 2uF for the discharge main capacitor. Has a hard life that cappy. Exciter coil under the magnetic flywheel runs about 300-400Vac at variable frequency. Idle about 16Hz ( cold crank perhaps half of that ) 4Krpm 66Hz, pretty low frequencies to my mind. In the case of the HKZ, three scr's internal, one a shunt regulator to clamp the DC HT on the main cappy at about 350Vdc ( seen 400V on some units ) the other two scr's fire the L+R and Center coils. Cut the face off HKZ and repaired them, like you, a long time ago now.... those 1ohm mini coils are however very well made on the HKZ.

Though this Mirage may well be BTZ, inductive discharge. See what transpires.

Glad to read of the iis old time service, did in the day use best i could purchase for passive and active components. The technology changed halfway through the production and i had to redesign from through hole to smd, which while a task at the time, made a big difference in simplification ie two layer board to a single layer board. As it may be of use, there remains many new old stock parts here for repairs and similar. Save for the UK suplied harness wire, cannot be bought for any money now. Tah for the post.... j
 
iis_iis said:
Yes Bruce the dump voltage capy to ignition coil primary, is in the 300Vdc range, around 2uF for the discharge main capacitor. Has a hard life that cappy. Exciter coil under the magnetic flywheel runs about 300-400Vac at variable frequency. Idle about 16Hz ( cold crank perhaps half of that ) 4Krpm 66Hz, pretty low frequencies to my mind. In the case of the HKZ, three scr's internal, one a shunt regulator to clamp the DC HT on the main cappy at about 350Vdc ( seen 400V on some units ) the other two scr's fire the L+R and Center coils. Cut the face off HKZ and repaired them, like you, a long time ago now.... those 1ohm mini coils are however very well made on the HKZ.

Though this Mirage may well be BTZ, inductive discharge. See what transpires.

Glad to read of the iis old time service, did in the day use best i could purchase for passive and active components. The technology changed halfway through the production and i had to redesign from through hole to smd, which while a task at the time, made a big difference in simplification ie two layer board to a single layer board. As it may be of use, there remains many new old stock parts here for repairs and similar. Save for the UK suplied harness wire, cannot be bought for any money now. Tah for the post.... j
Click to expand...
Yes John, I remember when you went to surface mount. I don't like it as my old eyes can't see anything when it becomes time to repair something that is surface mount. I have a hard enough time putting a scope probe on a SMD board let alone trying to solder something on it! If you ever design another ignition, use vacuum tubes, these I can see and know how to fix.


And finally for those out there with a Moto Witt that decides when it is getting dark and cold and you are many miles from home and the ignition dies, it does not like voltages above 14.5V. The ND regulator on my RGS would go to 15.3V after a few miles of riding. It drove me crazy trying to figure out what was wrong. It would never fail at home with test equipment waiting beside it to see what the problem was. Replaced with a Shindegen FET shunt regulator and all was well. I also have a Shindegen FET series regulator but have not tried it.

The IIS ignitions don't seem to care what voltage they see.
 
Last edited:
Nash said:
Im new on here,in fact I’ve never asked for help on line before.
I have a Mirage 1978. This is the problem.
I want to get it on the road this year but when I push the button I only get a spark on the two outside plugs and nothing on the middle plug.
The strange thing is there is only a single spark on them, then nothing.
I have had to replace a coil on it before.
I don’t mind having to do that again but I just want to be sure that is not the CDI.
Ive had this bike since 1987 and hardly been able to ride it because it has been nothing but trouble.
In fact I spend most of the time hating it but I kinda love it at the same time.
Thanks for any help.
Nash.
Click to expand...
Hi Nash, the best solution IMO is to bite the bullet and get a modern and totally reliable ignition/charging system fitted, there are a few to choose from but i have an Ignitech fitted to my 77 Jota and it transformed the starting and running...not cheap but you wont look back once its done.

You are also in the right place for information, this forum is second to none for knowledge and good friendly advice...hope you get things sorted.
 
The Automotive industry required higher grade electronics, superior reverse voltage protection ( back emf from alternators de-energised ) superior input voltage and differential ratings, no news to you Bruce. The poor old LM7812 or 7805 was out of its class in automotive applications, low cost and high performance, LM2931 5V regulator has proven a worthy protection and regulator in the IIS designs. Opto isolation of the uProcc, input and output signals another must have, a hardware watchdog timer LTC1232 ( was not cheap ) included even though the Uprocc had its own internal on chip watch dig timer. So on the design progressed as i would have an ignition system with best performance, cost was secondary factor.

Call in to your dentist Bruce, like i did, their brochure has every manner of eye wear to assist on working with items we can no longer see, the last soldering job i did was on DSP Sharc had 8mil ( 8 thou ) spacing between solder legs, all but did my eyes in... as for ball grid array...it was the end... yes thyratron ignition may well solve the eyesight conundrum. j

MFG_ADSP-2156x.jpg
 
Pretty agricultural method there Cam for this person, on the iis qfp proc i did perfect the blob across all pins then by capillary action "pull" the solder pins and pads clean with one swipe orthogonal to the pins/pads, you get real good at it, not too mention saving thousands on a rework station... clue was high quality rework flux to assist in the capillary wetting action.

The more dense pins like the DSP chip above the wetting action did not work, they stayed shorted, used a 0,1m/m tip soldering iron and ultra fine cored silver loaded solder and held my breath and solder all 176 pins one at a time... if they did short i used an ex disposable razor blade on an exacto knife handle and pulled the short out while solder tip applied...all new to me, these techniques, can do the repairs, just do not look forward to it at all. j
 
A relo with vision problems bought one of these from Vision Australia and it worked well for day-to-day stuff. I just had a browse through Vision Australia magnifiers, bloody hell most are Electronical and powerful as hell and cost well north of 2 grand, time moves on.

LED Illuminated Clamp Mount Magnifier | Jaycar Electronics

Powerful 125mm diameter 3 dioptre lens brings tiny items into clear view.
www.jaycar.com.au www.jaycar.com.au
 
Older Dentist use top grade optics with focus capabilities, see what can find out, BTW i bought two Ex Prince of Wales hospital Carl Zeiss Microscopes, no objectives alas.... came from the Pathology labs, 1950's type.... well made would be a poor reflection on the mechanisms, amazing of the era. j
 
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