Monday, February 2, 2015

Refitting HT Leads Into Nippon Denso Coils.

Misfire in the Wet? Weak Spark?
Sat under the tank, they tend to get forgotten. But the leads that take the all important spark to the plugs need to be fully-insulated. If moisture gets in where the coil makes contact with the copper-cored plug lead, your 40,000 volts will probably make its way down the side to earth, rather than putting a spark across your plug electrodes. Why? Because it's lazy and wants the easy path. Wouldn't we all?
If you've ever touched a distributor cap, or lead, on an engine with a misfire, you might have felt the same sort of kick. It's easier to find a path to earth through you, than fire a spark across two metal points that are 0.75mm or more apart, especially in a cylinder containing high pressure air/fuel mixture.
The same can be said for the other end where your plug caps are. The rubber sealing boots are falling apart on the GSX's caps, so I'm putting new NGK's on it. For the price of them, it's not worth taking chances.

So what's that got to do with the price of fish?
Well, the original retaining clips for the plug leads had long since made for the hills. When the bike came to me the HT leads were hanging in by the fact that they were completely rigid and couldn't move, and a bit of good luck thrown in. Don't get me wrong, the bike ran fine, but it would have been different in rain.

Later coils did away with the clips altogether, and came factory sealed with a resin of some sort. As much as I would like them to go back together as Mr Denso wanted, without new clips, I'm going to have to seal them in semi-permanently too.




I cleaned out the little tubes, where the leads go, with brake clean and compressed air. Then it was time to mask them up.


Work out how deep the tubes are by inserting a screwdriver, then apply masking tape on the leads at the same depth. The masking tape lets you know you've pushed them fully home before you seal them, and stops the leads getting covered in sealant.


Push all of the leads in first to make sure the terminal in the coil pushes in exactly where you want... and that, my friend, is perfect.


Probably overkill, but this stuff sticks like sticky stuff.


Once mixed, I applied with a screwdriver and let it settle into place for a bit.



Before it dried I removed the masking tape because, once it goes off, that stuff doesn't play well. Hopefully the leads haven't moved away from the terminal inside and the sparks still come out the plug end. The sealant does flex a little so shouldn't break when the leads are moved into position. Here's hoping.


New suppressor goodness, up against the oldies. Must get this thing running soon!