Scooter Ignition Coil Details

[earlwb]

I have noticed that quite a few people are confused as to what a ignition coil is and the spark plug boot and spark plug wire.
So I made a thread up here in an attempt to hopefully explain it better. Please feel free to add more information or explain it even better than I can.

Basically, on a new ignition coil unit/assembly, the spark plug wire is left loose at the spark plug cap end. This is to allow you to cut off the spark plug wire to length, as it is normally too long. But if you cut the spark plug wire shorter, allow for the fact that the engine pivots up and down as you go over bumps, so yopu need some slack there. Sometimes the factories building the scooters and assembling them dont screw the wire down snug into the spark plug boot, so the wire is loose. I have seen them where they hurriedly just push the spark plug wire on partially.

So what you do is peel back the rubber seal and gingerly turn on the wire while holding the spark plug boot and ensure it is indeed screwed on snug. Then pull the rubber seal back down over it. In some cases the wire end is all buggered up and loose, you usually have a lot of extra wire length, so you can cut off the wire end a little and re-screw it back on snug.

If the spark plug wire is loose or the spark plug boot isn't plugged onto the spark plug all the way, it creates a gap that the spark has to jump before it gets to the spark plug itself. This causes abnormally high voltages, which will cause the ignition coil to fail prematurely, as the internal coil windings will short out eventually. Also abnormally high voltages can get through pinholes or defects in the wire insulation and not reach the spark plug.

Here is a pic of the ignition coil unit.


Here is a close up of a spark plug boot or cap:


Inside the spark plug boot's socket is a reversed sheet metal screw as shown here:


Here is the ignition coil itself:


Here is the screw inside the igntion coil socket.

[unknownsoldier]

Good info here, thank you.

[swakk]

some friends reported to me that soldering the wires with silver improved the spark
do not have pict to prove this, but i think it could

[earlwb]

That might work to help keep the ends from loosening up on the screws. I have seen where the factory simply pushed the spark plug wire down onto the screws instead of screwing the wire on. That leaves it loose. Which causes it to fall off later. But the silver solder would only work on the copper core spark plug wires. Many scooter spark plug wires are the carbon core version to reduce RFI. So you can't effectively solder the carbon core. So you would need to get a length of copper core spark plug wire to do that silver solder method.

[doclane]

A friend of mine gave me a 3 foot piece of Accell high performance spark plug wire. Can i remove the ends from my existing plug wire and put them on the new one?

[hjn97]

Jul 4, 2008 12:49:54 GMT -5 doclane said:

A friend of mine gave me a 3 foot piece of Accell high performance spark plug wire. Can i remove the ends from my existing plug wire and put them on the new one?

Yes. Just unscrew the coil and the plug cap(see above pictures for each one), and screw them onto the wire.

This is assuming the wire isn't too thick to fit into each one. Also....use as short of length possible for the wire. More length equals more ohms.

[earlwb]

But do allow for some slack in the spark plug wire, it cannot be as absolutely as short as possible. The engine pivots up and down on a hinge joint, so you need to allow for some slack in the wire so that when you go over a good bump it doesn't pull the spark plug wire off on you.

[wildbill]

good thinking . thanks