Modern Guzzi Plug Leads

[Kiwi_Roy]

I bought up the subject on a couple of other threads nobody seemed too concerned about it but I feel the plug leads should be continuous.
The resistance I have measured on earlier bikes generally seems to be around 8,000 Ohms which consists of 5,000 ohms for the resistor cap and 3,000 Ohms for the coil assuming the leads have copper core wire, anything goes with carbon core resistor wire.
 
Obviously if you can't measure some sort of reading and it's over a Megohm or Infinity there's an arc happening in the lead (spark has to jump a gap)
This doesn't apply to a double ended coil or single coil with distributor of course.
I would appreciate it if owners could measure the resistance from plug cap to chassis

For example I measured my new V7 at about 6,000 miles.
One lead measures 30 MegOhms the other read infinity. See below
 
It might be interesting to measure a number of bikes to see if they are consistent.

I may be wrong but I suspect the faulty leads are contributing to poor running and perhaps the early demise of plug caps.

If you can be bothered please list Model and year, Lead 1 Ohms, Lead 2 Ohms, Lead 3 Ohms, Lead 4 Ohms. (1400s have 4 coils)
Just take these readings while doing a service when you have the rocker cover off that would be great. I don't recommend pulling the leads apart just to make this measurement, I think that's likely to cause more problems.

Heres a video I found on testing HT leads.
https://axleaddict.com/auto-repair/Checking-spark-plug-wires-using-two-simple-strategies
Note the author calls for 10-12,000 Ohms per foot for resistor cable so he would reject both of my V7 leads

Thanks in advance,
Roy

[Tom H]

'04 EVT

8.6K Right, 8.5K Left

This is from the NGK 5K cap through the coil to a rocker cover bolt.

Tom

PS: this is the 25ish year old coil wire from my Eldo:

[RinkRat II]

      2000 V11 Sport   R 8.24k ohms   L  8.17k ohms  Caps to frame.
   
        Paul B

[Kiwi_Roy]

Tom H, Rinkrat II
Thank-you Gents thats about what I would expect.
No nasty resistor cable there I'll be bound.

Now if I can just get a few post 2010 owners to respond.

[malik]

2010 V7C.  R. -  7.99.  L.  -  8.68 (when I could get it to sit still).

Might be something a little off in there - I'll check with another meter, check the HT cable ends (copper cored) & swap out the caps & try again. Of course, I didn't write down the readings when I last fixed it, some 90,000 km back.

[Kiwi_Roy]

2010 V7C.  R. -  7.99.  L.  -  8.68 (when I could get it to sit still).

Might be something a little off in there - I'll check with another meter, check the HT cable ends (copper cored) & swap out the caps & try again. Of course, I didn't write down the readings when I last fixed it, some 90,000 km back.

Thanks Malik note how different my V7iii is with resistor core lead. Did your bike come with copper?

(Quote - "when I could get it to sit still") You could also try switching the leads around, a different reading would indicate some moisture caused corrosion. I assume that reading is Ohm not Megohm
To get a good contact with the cap I used the nut off a plug screwed to an old spoke, try to avoid skin contact although it shouldn't make much difference at that low reading

[mechanicsavant]

You’ve piqued my quriosity . 2016 V7II 35.6 mega ohms left cyl.  Infinity on right side !

[malik]

Thanks Malik note how different my V7iii is with resistor core lead. Did your bike come with copper?

(Quote - "when I could get it to sit still") You could also try switching the leads around, a different reading would indicate some moisture caused corrosion. I assume that reading is Ohm not Megohm
To get a good contact with the cap I used the nut off a plug screwed to an old spoke, try to avoid skin contact although it shouldn't make much difference at that low reading

Yes, Roy, still the original leads. Copper cores.
I also presume the reading is in ohms - these cheap meters are not rigorous with their labels - there's a presumption you know what you're doing.
On the V7C, the original caps, and the current ones, grip the threads of the plug end (the round nut on the end has to be removed). The V7S' original plugs fitted a solid plug end, too easy to get a bad connection, so I changed caps & plugs so I could guarantee a decent connection on the thread of the plugs. I think I might still have half a spoke up at the shed (though it may be stainless), all the others are still on wheels, but I get the idea. I'll have another go when I get up there in a few hours.

[Kiwi_Roy]

You’ve piqued my quriosity . 2016 V7II 35.6 mega ohms left cyl.  Infinity on right side !

Similar to my V7iii
Note how Maliks V7C is only a tiny fraction at around 8k
I don't know that it makes any difference to running but I suspect high resistance puts more strain on the coils.

[malik]

OK. I think I've got my head around it. The V7C has 5k ohm resister caps and I've been measuring with the dial on the new (also cheap) meter at the 20k ohm setting.

R - 8.01k ohms - cap alone  - 4.80k ohms - wire to coil - 3.22k ohms
L - 8.72k ohms. - cap alone - 5.52k ohms - wire to coil - 3.20k ohms.

Nothing from the 2014 V7 Special - it's dismantled at present for the clutch (& now gearbox) and I get only null readings. It also has some fancy coil arrangement, with nothing there accessible. I guess, until I NEED to know more, they can stay as black boxes, shrouded in plastic super structures.

Hope this makes sense.



Mal

[Kiwi_Roy]

Mal,
      Thanks for the additional information 
I have a V7 Special also with very high resistance and infinity perhaps there is something different about the coils on this bike that's the idea of this post to try and figure out what's going on,
why are we getting an open circuit on a new bike?
I'm used to seeing about 8k from cap to chassis as you did on your older V7
Looking through my manual it shows resistor plugs also.
Carl's drawing shows different coils left and right although it may just be that the un-used terminal was left off.