Diagnosing secondary ignition problem

[gstallons]

FYI , when I was trying to figure out the misfire on the black frame bike you can do this very quickly . I used an analog meter set on the highest scale of resistance and went from the HT lead to the frame and checked for continuity . This verified (infinite) an open circuit. I unscrewed the cap and checked it . These caps have resistors and have a different r value . Since it was open I knew I had found my problem. Installed new cap and tested again .  Around 15k , so I knew everything else is good. The factory wire is a solid core and should be less than 10 ohm resistance . When you add the secondary value of the ign. coil to the test it will be more . It will be unusual for both sides to be messed up . Some service manuals give the primary / secondary r values. 99% of the time the secondary fails on a ignition coil aka transformer in a A.C. circuit. Remember this.  

If you are not sure about what you are doing or if you are not doing it correctly , go to the other cylinder and check your work . It is seldom both sides will be messed up .

[Weegie]

Agree with everything you said

In the past though I've had carbon and copper core HT leads return low resistance values, leading me to believe they were good, when hunting misfires and poor running.

Eventually after checking everything else and in desperation replacing the HT leads to find that they were the culprit all along.

The carbon cores are fragile and I reckon copper ages (oxidation or perhaps the high voltage degrades them in some way?............no idea) reducing the ability of the leads to transmit the high voltage.

Just saying if everything else checks out and the leads are old replacing them is worth a shot

[gstallons]

I don't remember the resistance/ft of non copper HT leads . I used to know . I used to have a meter that connected to each plug wire and gave a digital reading . High Kv output meant an open wire . Low Kv meant a fouled or bad spark plug.  The most likely failure on a spark plug wire is an open . 

On these V11s these wires are copper core so they will / are not prone to failure. Now the resistor cap is designed / used for two reasons. #1 to stop RFI on AM radios . If you are old enough , you will remember the noise a vehicle made w/solid core wires. Also , resistors are made into spark plugs . AC Delco R44TS spark plugs . The R stands for resistor built into the spark plug.  #2 Also , the resistor made into the cap give a more precise spark delivery .

Weegie , I didn't fool w/the wires because they were difficult to get to and I was satisfied w/my work . I was happy when it started and ran 5 seconds. You have no idea how bad this was running !

[Weegie]

I didn't mean the comment to be particularly relevant to your problem, I merely raised it for anybody, perhaps searching for solutions with a similar problem.

Anectodally I find copper leads deteriorate over a long period of time, same goes for battery to starter motor cable, of course a lot depends on the quality of the leads/cable.

Anyways glad you got sorted and the bikes going well again

I wonder how many people these days have analogue meters, I still have an AVO and love it, a beautiful piece of kit

[gstallons]

Mmmmm. AVO ? I just Googled it . Now to eBay to get one ! 

I have been bit using a DVOM looking for V and R in a circuit.  Reason : impedance . The DVOM will not load the circuit . An analog meter will. If the circuit will support a test light or an analog meter , I will get a true reading. 

 I had my @ss handed to me diagnosing the A.C. on a Kubota tractor on an island in the Miss. River after about 4 days getting 13v dc at the compressor coil . I put a test light on the + wire of the connector to see the V disappear. Put the DVOM back on the + wire and my 12v reappeared . I found the contacts of the temp control or relay were bad . New part and we were in business .  I use a DVOM for entertainment purposes only or when I need an exact "value".

 BTW , I have two Simpson 260 meters and a SnapOn MT 406 along w/a bunch of things my dad had . It seems funny when you pull these out and people don't have ANY idea what you are holding ! 

Also , the only time I get offended (spelled perturbed) is when things are not going well w/the conversation .

[guzziart]

FWIW, I replaced my plug wires about 4 years ago with NGK CR5 plug wires during a tank-off because one of the oe wire boots had obvious damage.  I now see that the cr5's have been discontinued.