ETZ 125 1991.No Spark.RESOLVED

[Puffs]

Very sorry to hear that, then something else is wrong.

The conventional battery-coil-breaker ignition works as follows:

1) When the piston has moved far enough below TDP, the contact breakers close & make contact. That closes a circuit, wherein current flows from the battery '+' through the primary part of the ignition coil, to earth (='-').
2) The ignition coil actually consists of 2 coupled coils, in the arrangement of a transformer: the magnetic flux generated by the current in the primary coil also flows through the secondary coil.
3) The 2 poles of the secondary coil are the HT lead (= '+') and earth (= '-', commonly the metal outside). The connection is made by clamping that to the frame. The 2 poles of the primary have M4 or M5 pieces of thread, with nuts on them.
4) At a suitable moment just before TDP on the compression stroke, the contact breaker opens again, and breaks contact. So the current that was flowing through the primary is interrupted, and stops rather suddenly, and consequently the magnetic flux also stops similarly. Coils react to that by generating an induction voltage (proportional a.o. to the rate of change of the flux and the number of windings).
5) The induction voltage in the primary causes a spark across the contact breakers, and to mitigate the burning-in effect of that, a small condenser (= capacitor) is put in parallel. Have you tried it with that condenser connection pulled off?
6) The secondary coil has more windings than the primary, hence generates the higher voltage, and that discharges over the electrodes of the spark plug. And ignites the fuel-air mixture, that pushes the piston down. --> 1)

None of the mechanical work you mention should influence the ignition. But I don't see a reply on the condenser, are you sure it is OK? The idea is to try while still connecting to the contact breakers, yet bypassing the condenser. The condenser might be faulty, so that contact is not properly broken when the points open.

If it is not your condenser, not your coil, not your battery, you'll have an electrical continuity problem somewhere, either in the primary circuit or in the secondary.

[JamesP]

Thanks for your extensive reply. Really appreciate and trying to get my head round it.
I have a new condensor , I disconnected the condensor and tested the points with meter but no change,.

I have been trying to set the points but they are wide open at TDC, not BTDC. At 2.5mm BTDC the points are closing again,
I cannot adjust points to sort this out.
Could the cam be out of line or is there a problem with the crank shaft?

Very sorry to hear that, then something else is wrong.

The conventional battery-coil-breaker ignition works as follows:

1) When the piston has moved far enough below TDP, the contact breakers close & make contact. That closes a circuit, wherein current flows from the battery '+' through the primary part of the ignition coil, to earth (='-').
2) The ignition coil actually consists of 2 coupled coils, in the arrangement of a transformer: the magnetic flux generated by the current in the primary coil also flows through the secondary coil.
3) The 2 poles of the secondary coil are the HT lead (= '+') and earth (= '-', commonly the metal outside). The connection is made by clamping that to the frame. The 2 poles of the primary have M4 or M5 pieces of thread, with nuts on them.
4) At a suitable moment just before TDP on the compression stroke, the contact breaker opens again, and breaks contact. So the current that was flowing through the primary is interrupted, and stops rather suddenly, and consequently the magnetic flux also stops similarly. Coils react to that by generating an induction voltage (proportional a.o. to the rate of change of the flux and the number of windings).
5) The induction voltage in the primary causes a spark across the contact breakers, and to mitigate the burning-in effect of that, a small condenser (= capacitor) is put in parallel. Have you tried it with that condenser connection pulled off?
6) The secondary coil has more windings than the primary, hence generates the higher voltage, and that discharges over the electrodes of the spark plug. And ignites the fuel-air mixture, that pushes the piston down. --> 1)

None of the mechanical work you mention should influence the ignition. But I don't see a reply on the condenser, are you sure it is OK? The idea is to try while still connecting to the contact breakers, yet bypassing the condenser. The condenser might be faulty, so that contact is not properly broken when the points open.

If it is not your condenser, not your coil, not your battery, you'll have an electrical continuity problem somewhere, either in the primary circuit or in the secondary.

[Puffs]

On adjusting the ignition: have a look in a manual (Blurredman's website, see his signature in the 2nd post of this thread). The points should start to open around 2.5 - 3.0mm BTDC, say 2.7mm BTDC.

On pulling the condenser connection off: looking at the pics, I see I had another bike in mind, where you can just pull the wire that connects the condenser off. On the ETZ you have to undo the screw in the top of the condenser, it gets a bit more difficult.

You can check if the coil & both circuits (primary & secondary) work quite easily: just put a plug in the cap & lay the plug body on earth, so that it connects properly. Pull the green wire off the connection with the breakers/ connecting strip/ condenser, and you can then easily simulate the opening/closing of the breaker, while bypassing the condenser: pushing the connector on the green cable to earth simulates "breaker closed" (so primary coil is charging); lifting it off earth simulates the breaker points opening. So you can test that part of the ignition (when you switch on the ignition): lifting the connector from earth should give a spark in the plug. Look at the plug in the shade, in direct sunlight you won't see any spark. If it does spark, that means that the problem is in the condenser, or in the contact breaker. No spark means the problem is upstream of that green cable.

Then bypass parts of the circuit to find the problem, for instance as parrbd suggests: a direct line from the battery + to the + of the primary coil. Make very sure you pick the right connector! If that makes no difference, then disconnect the cable that connects to the - of the primary coil, and connect an external line there. Leave the other side open: if you push that side of the cable onto earth, the coil charges. And if you then pull it off, you once again simulate opening of the breaker points, and you should get a spark. If not, either your coil is busted, or the problem is in the secondary circuit, or your battery is flat by now.

Good luck.

[JamesP]

RESOLVED.
OK, we have found the issue.
The wire from the condensor next to the points going back to the coil was faulty. It let some current through but not enough.
Replaced wire and we have a great spark and starts first kick for now.......

Thanks all for your help, much appreciated.
If you can change the title to Resolved it might help others.

[Blurredman]

Great news..

Something so simple caused so much problems..

[Puffs]

Excellent!