AJS & Matchless Owners Club

What has been said about cleaning modern plugs with wire brushes is correct but you can clean them with a blow torch which will burn off the carbon. or you can use oven cleaner which can be sprayed into the plug and then cleaned off with a clean thin cloth or tissue wrapped around a thin stick or other thin implement. However the root cause of the sooty plugs are as you said the carb is running rich. Altering the tick over settings will really not have too much of an effect or unless you are riding with the throttle wide open and hence on the main jet the richness will be caused on mid range running. So assuming you have the right cut out on the throttle slide dropping the needle a notch or possibly two should cure the richness if not your needle jet is probably worn so get on to Surrey Cycles and get them to send you a new needle and needle jet and set the needle height as per handbook. Take her out for a run and get the engine hot and on return check the plugs again. Remember, it is better to run slightly rich rather than weak as running too weak can put a hole in your piston. The last thing you should play about with is your float height but if the new jet and needle does not cure the problem don't forget that incorrect ignition timing can cause a sooty plug. I'm sure I don't need to tell you that if you run with the plug too sooty the engine will start farting and banging and you will end up cleaning the plug on the side of the road - my experience! Just a final point, if the plug is only slightly rich a hotter plug may be all you need. For Ngk plugs go down one number and for Champion go up one number for a hotter plug.

Tried that method Jonny b , but the wife objected !

56G80S wrote:I have used a toothbrush and methylated spirits and that has worked well for me.

Johnny B

ChrisTheChippy wrote:Tried that method Jonny b , but the wife objected !

To keep mine sparkling I soak them overnight with my dentures.

Sorry, that didn't occur to me, despite now 67 I still have all my own. It comes of being a fast runner rather than fighter.

Johnny B

This has just caused me to have a flashback of my old man putting plugs on the stove ring to burn off the old oil and crap out of them, then whipping them back in while they're still hot! I still do it occasionally

He also used mum's stove top to anneal head gaskets, which I also admit to...

56G80S wrote:Sorry, that didn't occur to me, despite now 67 I still have all my own. It comes of being a fast runner rather than fighter. Johnny B

My four originals are under a hedge somewhere along a country lane. Two loosened ones fell out later . I wear a full-face helmet now.

I came to this topic searching fake spark plugs as I have just bought some Champions and thought I'd check before fitting.
No real reason to suspect, but recalled seeing the NGK fake guide earlier in this thread and wondered if anyone has seen similar for Champion?

The only way I cured richness (and poor running) with both my premonoblocs was changing the body for NOS items and (ideally) also changing slides and needles. Bikes both now function perfectly.

Regarding plugs I have abandoned NGK's and am getting very nice fat sparks out of NOS period KLG's and Lodges from eBay. Last ones I bought had satisfying amounts of shelf dust on the boxes and the Smiths Industries corrosion resisting wrapping around the plugs. Don't know why, but I think the conductor wire through the insulator is heavier on these old plugs and they certainly suit magnetos better than anything new it seems. Probably worth cleaning, re-setting and hanging on to as the years and miles pass. I think one cost about a fiver and one a tenner but I was well pleased.

Iron Head