Triumphrat

ohiorider · 02-08-2008

Aside from the fact that the newer ignition systems can deliver a walloping jolt (some books claim potentially lethal), they can be damaged in ways that wouldn't harm an old system that uses points and condenser.

Every BMW I've owned since 1986 (10 of them), including the 1991 R100GS, has been equipped with a Bosch Electronic Ignition. And every one of the User Manuals cautions about cranking the engine over, or running it, with a plug wire disconnected.

Quote from 1991 Haynes Manual for Airhead BMWs: "Never allow the system (electronic ignition) to operate with either one of the HT (spark plug) leads isolated as the very high voltage may damage one or more components of the system."

The Haynes Triumph Manual for our bikes states basically the same thing. " It is vital that the engine is not turned over or run with any of the plug caps removed, and that the plugs are soundly earthed (grounded) when the ignition is checked for sparking. The ignition system components can be seriously damaged if the HT circuit becomes isolated."

Neither of these manuals spell out which specific parts can be harmed, but I suppose they mean any and all components.

I'm posting this only because some of the Triumph riders on this Forum have been away from bikes for several years; for others the Triumph is their first bike ever. Most of you who have been riding bikes with electronic ignition systems are already aware of this.

Bob

bendavanza · 02-09-2008

I know several sparks were (not) made on my bike without harming the system, but I may have been lucky. I read the same information after having tested for spark...
-Ben

Binnsy · 02-09-2008

So, does that mean that when you get a breakdown in a lead or plug, it may damage other components??

ohiorider · 02-09-2008

Quote:

Originally Posted by Binnsy

So, does that mean that when you get a breakdown in a lead or plug, it may damage other components??

I don't know. I can only believe that if an ungrounded lead (during testing) can cause damage, that an ungrounded lead due to a component breakdown (example - broken and ungrounded HI tension lead) could cause a similar problem. Anyone else want to weigh in on this?

Bob

Tbirdnz · 02-09-2008

I believe modern ignition electronics should be able to protect against an ungrounded HT lead, the earlier types could not.

Having said that I still would always ensure when testing a plug that it was grounded, without grounding the electrical circuit isn't completed.

I'm open to other suggestions but that's my take !

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Ride on !

mjtool · 02-09-2008

FWIW the GM manual says not to crank the engine over with more than 2-3 plug wires disconnected. Not sure which component could be damaged there either but it is another situation where they warn you not to do it.

mike

CommandoRdster · 02-10-2008

Don't do it even with a points set up.The most likely component to be harmed is the coil.Remember how in the Haynes(and even factory) manuals for the old twin carb Brit bikes they recommended setting the idle?Pull off a plug wire so it was only running on one cylinder,then set the idle on that cylinder so the engine would fire twice,then die.Repeat for the other cylinder.I can't tell you how many fried coils I have seen due to this maneuver.

This is actually a pretty good way to set the idle on those bikes,and a fast mechanic can get away without doing too much damage,but us regular guys have a little jumper we use to ground the plug wire.

All that juice has to ground somewhere,and it will cut a path right through the insulator if it needs to.It just happens that much faster on a modern,high energy system.

You can get away with doing this on a car,or at least one with a distributor,because the juice can jump to the next pole on the distributor cap,just ruining the cap,rather than the coil.But distributors in cars are going the way of points and condensers,so beware.

On CDI set ups,like lots of bikes had back in the '70s,you could fry the capacitor just by kicking the engine over with an ungrounded plug wire.I have an expensive first hand memory of that!

On a transistorized EI, if the spark at the coil jumps to the negative post,it will try to ground through the module,which is not designed to handle that kind of voltage.Not pretty.

It's usually a good idea to keep that plug wire grounded.

Binnsy- Theoretically it could,and I'm sure has,but electricity will take the path of least resistance.If the HT lead is deteriorated to the point that it's open,it's easier for the spark to jump to ground through the relatively thin,probably cracked,insulation of the wire,than to try to jump at the thick insulation of the coil.Likewise an open in the plug itself.And,if it's fouled, then it's basically shorted,so the juice is going directly to ground.And if the plug actually gets worn to the point that it will no longer fire,the bike has been running so bad it's been unrideable for a long time anyway.

Cheers!
Bruce

Wooly · 02-10-2008

If you look in your owners manual, towards the back, there is a procedure for long term storage where Triumph recommends to remove the spark plugs and pour a little oil in each bore then turn the motor over with the starter to oil each cylinder.

They make no mention of having to ground the spark plugs first, perhaps they assume everyone knows this is the correct way to do it, maybe not.
I was surprised to read this advice having noted that the Haynes book says to ground the plugs first as a precaution.

Do Triumph know something we do not?

Bottle_Fed · 02-10-2008

Yes Bob, you are absolutley right! It's because on a waste spark ignition the spark has to travel somewhere. Whether it's arc'd between two plug wires, spade terminals, or internally, it is going to fire. Of course we all know if the coil arcs internally, it's fried! However, if you have a plug grounded it gives the spark a path to follow instead of making it's own.

Greg

stu · 02-10-2008

Some time ago I purchased an imitation spark plug that clips onto any suitable ground for just this reason. It has an adjustable gap so you can also check spark strength. I believe it came from a Moss Motors catalog (Brit cars) but it was a few years back.