Spark plug cable replacement

[u/fotzenbraedl]

The previous owner of my Guzzi obviously used to unplug the spark plug cable by bending the jack, so I found the rigid central part broken and now the outer rubber part broke as well. (First picture, spark plug cable end out of focus. Not shown: There was a small loose spring in the tube.)

Spark plug hole with broken jack

Short question: I could replace just the rubber coated jack --it has its parts number printed on it-- or I could prepare to renew the whole cables since it is said that spark plug cables are subject to wear, too, and I'm not really sure how to test if the jack gets proper contact to the cable. What is better? Do motorcycle spark plug cables age? My bike is 6 years old and passed nearly 1 earth circumference (40000 km) and I plan to never sell it.

Background: I could remove the spark plug cable cab just by turning it becaue there is a screw inside it that screws into the end of the cable. Interesting for those who will encounter a similar problem. Out of curiosity and as it is broken anyways, I shelled the rubber part off, see 2nd picture.

Removed half of the broken jack

On the rubber part, there is a part number and an electric resistance written (5000 Ohm). Now I can order that particular part from the spare parts shop, screw it onto the cable, hope that it gets proper contact and reassemble the rest. This can be the shortest way to make my bike running again.

Or I could order the whole cable, or even a pair of cables (for the other cylinder as well), lift the tank up and renew both of them. More work, more costs but better prospect to success (as long as I don't break something else in the additional work).

I'm looking forward for your opinions. And my next ride. 🏍️

[u/fotzenbraedl → u/[deleted]]

This sounds encouraging to really try the short way first. Indeed, the cable end is as you said, and it looks fabric new and felt elastic, so I'm keen to not even need to cut it. Also, you hint that the relevant resistance (5kOhm) is inside the cap, not in the cable, so I don't have to check if cable+cap has 5kOhm. Proper connecting new cap+cable will do it.

The spring was inside the tube of the cap that is cracked. Maybe it is part of the resistance? I first considered as a makeshift solution to put it back into the broken tube and have it all pressed together by the screws of the spark plug cover, but I concluded that it is too risky: Rather have all electric contacts well shielded from fuel fumes.

I appreciate your help. Thanks.