Coil power improvement (again)

shadowfax

shadowfax

New member
Location
Manchester, UK
Last started just before Christmas, all I have done is take the battery off and charge it

It is a BTZ system with 2 x 042 Bosch amplifiers (resistors?), and a single coil, and a twin coil on a 180 degree 1200

So, no spark at the plugs. I have now gone through the wiring.

Kill switch fine and engine turns over without any problems, so I assume the battery is ok.

With the ignition on, 10 volts either side of the ballast resistors, 10 volts into the coils. I cant believe that both coils would fail at the same time

I understand that there has been other posts that discussed just junking the ballast resistors all together.

I hear all these post about change the plugs, I struggled to see why that would make a difference as I have had many bike that failed to start, flat battery, blocked carbs etc, but once the plugs where cleaned and the fault sorted they have started without any problem. Having said all thatI did put some new plugs in, with the same results. If there is no spark it will never start.
 
Did you refit all the battery leads, and to the correct sides?
If all you did was remove and refit the battery I would start there.
 
Kill switch fine and engine turns over without any problems, so I assume the battery is ok.

With the ignition on, 10 volts either side of the ballast resistors, 10 volts into the coils. I cant believe that both coils would fail at the same time.

Assumption is the mother off all stuff ups.
First check to see you have a good battery should read 12.6 volts or higher at rest, if all good check resistance across your ignition coils + and - they should be 0.4 to 2 ohms. From ignition tower to + terminal should be 6k to 15k ohms
 
Apparently all he did was remove and refit the battery and suddenly no sparks.
 
While I don't have the same bike, I would look for the small wires leading to the coils. If you removed the battery, you may have pushed a wire and disturbed a small connector placed along the frame between the battery and the ignition coils. I've seen a 1200 loosing a wire connector this way and naturally if wouldn't start. The electrical connector was a bit Loose after many years, so came off easily, and no start. Next is taking a multimeter and measure resistance on every single wire, from battery, earth wires, ignition pickup wires, wires to the coils etc. Even measure wires to the kill switch and the ignition lock. Spray every single connector with a bit of electrical contact cleaner and use a few cotton swaps to clean old Black corrosion off.
I saw an internally broken wire right on the ignition pickup up, which could be saved digging a bit into the plastic material and rejoining the wires, then finishing off with a dab of epoxy. Worked fine for decades after that (my old RGS).
If you are using a more modern high tech battery, say an AGM or even a LiFe battery, they tend to Work with up to one Volt higher. So in that case, a reading of 12,6 is not enough. Normal lead acid batteries shows around 12,6-12,7 when they are fresh. Right after a charging of the battery, if will show more, but gradually drow Down to 12,6-12,7Volt.
I've seen a thin wire to the coils going bad and nearly broke off all thin wires internally under the insulation because of having been sitting for many years bent at a Sharp angle, and once the owner cleaned the bike in all the small corners, the wire became disturbed and the wire breakage showed as a too weak connection to feed the ignition coil, hence no spark. An example is to carefully move the thin wires a bit, when measureing resistance. You can naturally unplug the battery when performing this.
I've also seen many near new spark plugs going too wet during a start attempt, and once taken out, dried and cleaned, they looked super fine Again, but wouldn't fire any more under compression, but did give a nice spart in open air. That may vary from brand to brand.
Therefore, have a box with a few sets of spark plugs ready as well.

Kind regards,
Jacques
 
If your voltmeter is accurate, then 10v on the coils without cranking the engine (I assume) will never deliver enough to power the BTZ ignition amplifiers to deliver a spark at the right time, or at all!  Junking the resistors - whilst a good move - won't help with volts that low.  What voltage do you measure directly across the battery terminals?

You haven't answered Grant's question -
Did you refit all the battery leads, and to the correct sides?
Click to expand...
it's an easy mistake to get the smaller leads mixed / inadvertently swapped.

Then as Jacques explains - check any wires that you could have disturbed in removing / replacing the battery.
 
What voltage at the battery before and during when you press the starter button.
Maybe the battery is goosed.
 
Battery is good ....... voltage is fine. 10V across the resistors is normal btw for a Laverda.

I read some technical blurb on another thread that says thats normal and why Red suggested junking them. I've had a mate round who is a lot more savvy with electrics and he is wondering why the feed from the resistors to the coil is live when the ignition is switched off??

Coils are good, briefly shorted them out and all is good at the plug lead end

Otherwise he is of the opinion that it is the ignition unit that is goosed, but until he knows the reason why (is it a Laverda idiosyncrasy?) he is wary of fitting a new one
 
shadowfax said:
I've had a mate round who is a lot more savvy with electrics and he is wondering why the feed from the resistors to the coil is live when the ignition is switched off??
Click to expand...

WTF?  :o  I'd be wondering that too.  If that were true, then your battery would go flat in a few hours with the ignition switch in the off position. Not to mention the coils cooking themselves.

10V across the resistors is normal btw for a Laverda.
Click to expand...

10V across the coil maybe, not across the resistor. If you've got a 10V drop across the resistor, that only leaves 2V for the coil (they're connected in series). If that's the case, it's not surprising you have no sparks!
 
The feed to the coils wasn't live all the time btw, when re checking

Well, after finally tracking down the source of all my woes of the bike not sparking (not me but someone more familiar with the vagaries and magic of electrics) it seems the BTZ unit has gone kaput, hence no sparks at any of the plugs.

I've put a post in the Wanted section for one
 
shadowfax said:
no sparks at any of the plugs.
Click to expand...

Your bike basically has two separate ignition systems. One fires the two outer cylinders and the other fires the middle cylinder. If only one BTZ has gone kaput, you should still get sparks at the plug (or plugs) on the coil that's connected to the other BTZ box.

If none of the plugs is sparking, then either both BTZ boxes have died at the same time (which seems unlikely) or you've mis-diagnosed the problem and it's something common to both ignition systems.

Things that may affect both ignition systems are the power feed to BTZ boxes and coils, and earth connections to same. That's pretty much it. The BTZ boxes, coils and pickups all operate independently.
 
It lives  :D :D :D :D :D :D, turned out to be an earth ........... but also discovered a wire to a coil that fell off when disturbed.  Thats the short story, but cleaned every spade with emery cloth, sprayed every block connector with contact cleaner that we could find, reattached the coil wire.
 
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