Autonerdz forums

Found out why i haven't been able to get a signal for all these years.

It appears that the manufacturers have been using unmarked and unspecified anywhere shielded HT leads which is why with std type inductive clamps you get no signal. I used the scope and a cop adapter/extension HT lead but connected to the std plug cap and lead and hey presto waveform was revealed.

Hope this helps others as i never knew the oem HT leads were shielded , although make perfect sense now .

A bit of both to be honest and i have only tested this on one bike so will update this if i find any anomolies. But most of what i see is either CDI or Transistorised ignition control.

Anything i should be looking out for?

Hmm interesting.

I knew they shielded certain parts to stop interferance like some regulator rectifiers and such like. It makes sence that a ht lead would generate a much highter level of interferance than a reg rec.

I never noticed anything at the time & radio and workshop lappy was quite close and i never noticed it having a wibble and the bike ran the same even with the other leads run in series to the std ones. I will monitor it next time i hook up and look for signs of interferance.

I assumed that they used shielded HT leads as normally much of the main loom would run within an inch or so of the coil or ht lead so would be much more exposed to even "normal" levels of interferance than on a std automotive application.

I wouldn't replace the leads with non shrouded type as a repair as that may open a can of worms but for scoping the secondary waveforms i thought it should be ok as long as like you suggest there is no interferance that casues running issues or false/poor readings.

Any other thoughts on possible issues with testing along theese lines?