The Slow Death of The T3 Coil?

[phpbiker]

Hope its OK to start a new thread, but I thought it might make an interesting discussion?

As some of you guys might now, I had a non starter over winter, and it took a new set of plugs and an over night airing of the combustion chambers to get her running. She now runs. A1 as usual. Although Sometimes seems slightly rich.

But.. as ever... I have a theory.

I think its possible that with these coils, they degrade, and whilst the bike keeps running, that around the late 20's and upto the later 40K depending on use (miles this is not Km's) .. that the coils gradually go off and although the bikes carry on running apparently normally, the spark gets weaker and weaker.

I have some symtoms on my bike that I always thought might be because the machine was setup slightly rich, when in actual fact ..the spark is getting weaker and the burn is not quite right.

I once has a 1960's highly tuned Ford 4 Cylinder engine that despite being setup "perfectly" never ran properly always seem to be rich, in symptom but never actually was.

When I finally installed Hi-Po Electronic Ignition with a digital advance curve, it smashed its gear box twice and laid black lines on the road.

I think to a slightly less extent this is whats going on with my 29K Daytona T3.

I am hoping to add to the stable with a T595 soon. But I want the T3 running bang on. Its a matter of pride..

What you guys think?

The slightly rich running could be symtomatic of degrading ignition coils rather than jetting or carb setup.. which has recently been verified / balanced and generally double checked....

[KitNYC]

There is another theory that's been mentioned here more than once that seems to fit with yours...

The consensus seems to be that the most likely cause of the coil problems is their location: between the motor and the heat shield on the bottom of the tank, where the hot air goes. This location subjects the coils to enough heat stress that they eventually fail.

Certainly, it would make sense that this sort of gradual failure would have some symptoms along the way...

Cheers,
-Kit

[IrlMike]

It's an interesting possibility. The usual failure mode seems to be breakdown - shorting of turns - in the secondary windings. This of course reduces the energy available for sparking & the total energy there is of importance in initiating a good clean mixture burn. When my Legend had this fault, actually misfiring from idle to ~3k rpm (classic symptoms) I was 250 miles from home. So what I did was to pull the plugs & regap them down to ~ 25 thou. This has the effect of the coil secondary reaching a lower HT voltage before the spark jumps & the energy released. It didn't remove all misfiring but reduced it enough for the bike to get me home. That does suggest that there could be some progression to the coil failure where actual misfiring doesn't occur, but the energy available is reduced. (I didn't fancy a repeat of that experience, so replaced all 3 coils with Nology items.)

[phpbiker]

Yeah....

I chatted with an aquaintance who's a Yamaha mechanical (phhhh :-) ) ...

And he agreed that a weekened spark may make the bike run apparently perfectly, but actually not be a burn as designed.

He showed me a spark from a new Yamaha coil in the work shop and it was like a flash!

[trypcil]

My VW VR6 has coil issues. Heat doesn't flow properly with the flash looking plastic fascia that is sported over the head, the coils fail from heat - by just removing said fascia the coils don't fail.
With the Triumph's coil issue - heat affectation due to proximity to the engine, may contribute to the failure rate - yes. Though the nakedness of the bike extends to the poorly considered low tension connectors to the coils themselves. I suspect that there is a minute leakage of current even with the key out and the battery in, throughout the wiring - combine that with the exposed nature of the connection with time and the elements and heat cycling of the engine - I believe results in a electrochemical reaction that impairs the passage of electricity across the connector, that in some way contributes to the erratic function of the coil(s). Cleaning and attention to this interface, of those spade connectors, does prevent erratic running and extends the service life of the coil - erratic tachs can also be fixed by this simple procedure. Slathering the connectors in silcone to prevent this maybe an option - maybe I'll experiment along that line! Anyway the ghost of Lucas at this time of year, is never far away - it seems.

[KitNYC]

No question, those connectors are quite suspect as well! I mention the heat thing because the coils seem to fail even when the connectors are cleaned regularly.

Cheers,
-Kit

[ozjimmy]

I was going to ask what can cause a missfire or for it to run on 2 after it warms up. It runs well (not quite but well enough, I'm still trying to tune) when cold. And when I hold it wide open and it gets over 100k it starts to run on 3 again? I was thinking valve clearance or plugs.
Any clues

[N5XL]

Jim,

Coil, coil wires or plugs will do exactly this.

[IrlMike]

Originally Posted by ozjimmy

I was going to ask what can cause a missfire or for it to run on 2 after it warms up. It runs well (not quite but well enough, I'm still trying to tune) when cold. And when I hold it wide open and it gets over 100k it starts to run on 3 again? I was thinking valve clearance or plugs.
Any clues

As well as electrical possibilities....

Don't know if you're aware of the Mikuni slide/needle jets wear issue? Excess fuel gets by the needle causing misfiring/bogging especially at lighter throttle openings. Worse when the engine is warmed up. Steeper tapered aftermarket needles like Dynojet etc make it much worse. (I've only experienced it myself in this situation.)

[ozjimmy]

Thanks XL and Mike

I do have factory pro needle's. but have replaced everything less than 1000k's ago. So I'm hopping plugs then i'll look at coils and connections.

Thanks again.