Just on HT leads - Got some snazzy silicone ones (7mm OD) over Xmas and clagged them on - Loads of bother since. When screwing them in to the Coil and Cap they where going all the way down and you could feel them tightening up - Smashing i thought.
Twice now i have had a Pot off - when stripped down the leads were barely screwed over the coarse threaded pin on the coil and you could just pull them out.
Done a bench test over the week - it appears the silicone is that soft that appears to be getting "threaded" as you tightening it - But no - it is not forming a thread at all and appears to be "relaxing" out. With vibration of motor its just accelerated the problem when fitted to bike.
New PVC HT purchased last week (7mm OD) when rechecked at the weekend they are still tightened right up.
Only paid £6 for a meter of the silicone ones so it could be that they are just shite. - Very strange but true.