Loose coil-spark plug connection

[TigerShark]

On my '06 Tiger, I was surprised to observe that the spring in the coil that pushes onto the small threaded top of my NGK spark plugs fits so loose that I feel no resistance when connecting the two. I did this while holding the plug in one hand and the ignition coil in the other. Same with all three coils. In my experience, there should always be a tight connection, producing a notchy resistance when the coil is pressed onto the plug. Any insight on a misunderstanding on my part? Or is this normal wear, requiring a squeeze with needle nose pliers?

[Lee337]

You should feel some resistence when pushing the lead on to a spark plug. This indicates it's seated correctly.

Sounds odd, but a loose connection can allow electricity to leak. There should be good contact to avoid this. Leaving it loose could ultimately cause a misfire or rough idle. I had this on an old V6 Shogun I owned, which eventually eroded the connector. Had to replace the HT leads but to get me out of a jam, a good clean with some wet & dry, a spray with contact cleaner and a little tweek with pliers resolved it.

[TigerShark]

Thank you, Lee. Your comments support what I've always understood, but the fact that all three of my coils lack that assuring friction during installation really made me wonder if these 955 coils relied on an unconventional means of contact.

By the way, these coils with 123,000 miles on them, including many hours of stop and go heavy traffic, are each at about .5 ohms resistance across the two connector pins. According to my manual, spec is .7-.9 ohms. My meter is a quality unit. Any thoughts on this?

Doug

[Lee337]

I'm no expert on these & wouldn't even know how to check them without the help of the internet. I've been lucky not to need to replace them. The internals do break down after a while, the life expectancy is around 100k - 130k miles, or 7 years. Having said that, my 06 didn't have a problem & I had an 05 with 123k miles which was fine. I've heard 130k+ milers still going strong.

It might be something as simple as all electrical connectors needing a good clean & maybe some electrical contact grease (think it's called dielectric grease).

Sadly, finding replacements may be a bit difficult. Triumph show them as no longer available (part No. T1290006).

[TigerShark]

When running the primary test on my coils, I was metering .4-.5 ohms resistance. Considering that .1 ohms of that is attributable to my Klein test leads, .3 ohms resistance is quite out of the .7-.9 Triumph spec.

I went ahead and ordered a set of coils from RM Stator. Being in the state of Washington, their Colorado headquarters will have the set to me in two days.

Until now, I never thought of coils as wearing out. Always learning.

[TigerShark]

Forgot to mention, the spring in each coil actually does not grip the top threads of the spark plug, though it does encircle them.

The solid contact with the top of the plug is made during the bolting down of the coil; the downward pressure of the coil loads the spring against the flat 'shelf' that runs around the base of those tiny top threads. That is the spring seat when assembled.