Spark Plug confusion

[Goldy]

I used to own a BSA C15. I serviced it during the winter and when I came to start it up - no go. I knew it could not be the plug because it was brand new so I tried everything. In the end it was the plug and guess what make it was............ NGK

[BSA_54A10]

I got the blowtorch out on the faulty plugs until the centre electrode was glowing red and then kept going until the insulator was completely white again. Now they work just fine. At least I now understand the problem and will try to keep away from short runs and too much idling.

Direct heating the center electrode with a torch is just about the fastest way to kill the insulator.
You need to heat the thread till dull red hot and allow this heat to burn the crud off the center electrode.
The problem is right down in the bottom of the hole between the center electrode & outer electrode.
Playing a torch on the insulator can create a thermal gradient too high for it to tollerate and can cause cracks.
The tiny cracks will not be a problem at first but can make the plug go foul again in short time or worse still break up in service inside your engine.
You maye have lucked it in but please in future only apply heat to the outside (threaded) section.
Please be a little careful not to breathe in the fumes as some plugs have a cad plate finish on the threads.
After the center has burned to a white clean finish, wire brush the thread then apply a little copper ( or nickle is better ) anti sieze before you screw the plug back into the head.

[bsa-bill]

Hi Trev, yesterday as a diversion I scooted some "alloy Wheel Cleaner" down into an old plug and sat it upside down in a tin, left it for ten minutes or so and had a look, the end of the ceramic had cleaned, maybe if I left it a bit longer and give it a scrub it might have come up better but wonder what this stuff does to the surface of the insulator given that I think it is acidic.

Somewhere I also have one of those old spark plug cleaners that work of a twelve volt battery, it belonged to my Dad, I'd love to dig it out and try it.

[LJ.]

Bill... Isn't that a Gunsons, or Red Devil spark plug cleaner? Kinda like a mini sand blaster.

I find that using my workshop sand blaster cleans them up nice, be sure to carefully wash out in some white spirits afterwards to ensure no grit remains though.

[bsa-bill]

Hi LJ - it's a bit too scruffy to tell if there is a makers mark on it, should be somewhere though.
Sounds like it has small needles or similar inside, you know there should be second hand spark plug cleaners from garages to be had - must investigate

BTW are you the LJ mentioned in RC this last month

[Smithgd]

Id try the B6ES NKG's.
Champian plugs are crap IMO. I had one come apart in my Gold Star, and almost holed my gas tank. That was my last Champ. Be sure you have good Lucas brushes in your mag. I inadvertantly got a set of Asian repros in my mag. They were too soft, and left carbon tracks on the Ring, resulted in poor/eratic running. Engine Eventually stopped. Took me a month to figure that one out.

[LJ.]

BTW are you the LJ mentioned in RC this last month?

Yes I am! and staying with the writer Graham Ham & family this very Thursday for an early start to the John Bull rally this weekend. I've not yet read the mag though, should I take a big boxing glove?

Seriously... Graham is a great chap and inspired me to do the Round Britain Rally twice. I expect you might have read his brilliant book 'Daiseys  Diaries'... Well worth a read.

http://www.realclassic.co.uk/books/books05072900.html

[Apologise to Andy M for hacking his thread!]

[peter49]

Hi Andy, I had serious problems with my A10 failing on one or both cylinders when I used Champion plugs, i switched to using NGK plugs, and at the same time put  a fuelcat into the petrol tank, and have not had a problem with plugs failing in the last 500 miles.

[groily]

Sounds as if there are good and bad plugs of all makes to me. I've been running (the same) Bosch plugs in my (ironhead) A10 for over 20,000 miles and they're still better than fine, another of the same in my B31 and that's fine too, NGK B6/7/8s or Champion 5/4/3 in other things with alloy heads, and, yup, one or two very rare glitches. But that's in loadsa miles. I'm not big on changing plugs unless they've eaten their electrodes or are otherwise messed up, which usually says something else isn't how it ought to be. Sometimes I've found 'plug failure' is advance warning of a magneto (or other ignition) fault - but replacing the much-maligned two-buck item gets you home at least.
Dunno what a fuel cat is Peter, but if it's tin pellets in a canister or something I'd say it was probably snake oil, like those so-called spark boosters that wreck HT pickups and eventually destroy HT windings . . . Hope you're able to stuff a couple of noughts on the mileage to get proof out of that particular pudding!