Restoring Fouled Spark Plugs?

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The Standard

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Is it possible to get a spark plug that is fouled or excessively dirty restored back to the point of 100% capacity like when it was new or once they are damaged they should be thrown out?

The ask is for plugs with low/medium mileage and age.

I have heard of cleaning with certain chemicals is possible.

Has anyone had consistently good luck with those devices you just place the plug inside and I think it is media blasted of some sort?

For my application, with B8ES plugs becoming harder to find locally, re-habbing qualifying candidates is appealing.
 
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They used to sell, mostly for oily 2 strokes, little gizmos with hard steel bundle of wires that would shake - put nasty plug into the open end and shake shake shake, then blow out with air, or tap tap...fits in pocket. I have not seen one in 60 years. However Harbor Freight sells a little sandblast gadget. It works ok...but it is 100% necessary to get every particle of abrasive out of the plug. Otherwise it's come free in operation and do damage, bad damage. I sometimes use the sand blast gadget myself. Get every particle out of the plug. Repeat! Use magnifying glass and compressed air. Re-gap. File sharp edges on the sparkie parts...the spark jumps at a lower voltage that way, re-gap. Don't make dust near open machinery... like outside and down wind from the bike... Ask 'round. Good luck, at one time everybody cleaned and re-used, well, maybe not J P Morgan or Rothschild...
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Propane torch. Get it nice and hot... it's a spark plug, you won't overheat it. Heat it 'till the ground electrode glows even. Let it cool... small stainless wire brush to take the soot off... blow out with shop air... done.

Growing up on 2strokes, this was standard procedure.
 
Years ago, we used to clean our gas fouled (wet) two stroke plugs and re-use them all the time. At first we would just scrub them with clean gas and a toothbrush, then let them air dry overnight. Then we discovered electrical contact cleaner spray. With that, you could spray down a wet, gas fouled plug, scrub it clean with the old toothbrush, let it air dry (only a few minutes were needed) and put it right back into the bike.

If you're having issues with the 8's fouling, try a 7, a step hotter. Yes, 8's were the recommended heat range on the early bikes, but on later models, Yamaha switched the recommendation to 7's, and it's become accepted practice to run them on all models. Also, try the "BP" type (projected tip). When Yamaha changed the recommended heat range, they also changed to this type. It's also accepted practice to use this "BP" type in all models today. I don't think the "BP" type plug was being made yet when these bikes first can out, hence the factory recommendation for the regular "B" type plug on those early models.
 
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Been using a wire brush for over 50 years. The centre electrode is iridium or some other precious metal, the ground is nickel chrome, the outer is ceramic, how are you going to damage that without a hammer and chisel. Try taking one apart!
 
Carb cleaner then the propane torch.
Bought a junker TX750 it came with about 20 fouled BP7ES plugs, the guy must of bought a case of them.
All were hit with Carb Cleaner, torched put to use in XS650 motors with no issues.
Yamaha issued an SB calling for BP7ES in all XS650 years and motors.
 
It's a good idea to re-gap. and the spark will jump easier if there are filed sharp edge - and the copper gasket may not re-seal at very well - sometimes - it's essentially a one use gasket...but the copper can be worked off and heated, then quenched, which will soften it. Or one from a new plug can be used. Do not over torque. Antiseize is, iirc, well advised. Use compressed air to blow away any dirt before taking the plug out of the head. Also inspect threads...the other guy may have damaged things. I suppose I've used all the methods spoken of above. They all work. Don't leave the hole open - stuff can find its way... use "foreign material exclusion" like maybe screw in an old plug to assure than no bad stuff can enter the cylinder. I usually put in 3 drops (no more!) of light oil before I'm done. Prefer 3 drops of 2 stroke oil. It's not rocket science. Good for you to decide to ask and study so as to avoid bad outcomes! Smart! Bestaluck and fortune Amigo!

we have it easy...old time plugs were multi-part and screwed together...and leaked quite often. Video>
 
I used to routinely clean spark plugs with a Champion air/media blaster some decades ago, when I was being paid for it.
It was the done thing at the time, and nobody ever said anything negative about it.
Then I read about the dangers of grit getting down the bores - didn't seem like such a good idea after all.
Anyway, last year I bought my own air/media blaster and set to cleaning up a small basinful of plugs I'd accumulated over the years, taking a good deal of care to make sure no grit or shit remained in the plugs. They all turned out nicely and I'm happy to have a collection of plugs I can re-use when I need them.
I'd say 90% of these plugs weren't all that old in mileage terms, the ground straps on them and the centre electrodes were still fairly unworn. I'd been buying and trying different types just for the hell of it to see if it made any measurable difference.
One thing I can say, is that swapping to projected nose plugs definitely put a little bit extra zing in the step.
 
An ultrasonic cleaner can help getting the grit out if you are determined to clean the plugs. otherwise just buy new.
 
The need to change plugs can be urgent, arcing porcelain, broken bits, etc... but the fuel consumption increasing is often a subtle first indicator. Like fouled injectors on the old diesels - a hard run at load can do a fair job of clean in situ, depending of the fuel/air mix etc. (in diesels I add some acetone and 2 stroke oil first) Like, I don't change plugs on schedule, but on observation of wrongness, so to say. Adding that the plug temperature much depends on the proper torque - loose, they get hot. Maybe sometime make pre-ignition. Very un-nice! To check condition run about 20 miles and then pull a ton, if I can...gotta a "secret 2 miles" not very far from the digs. If she'll do as good as last time, she's ok. The evo and the sport will, the XS? I need to check, but probably.
 
We had a glass bead cabinet at work we could use for Govt jobs,
I've done the same plug numerous times with no ill effect.
Always ran the B8ES cause that's what the book said but they fouled often,
carried the extras in a saddle bag for quick change on the road side.
After some reading on the forum, definitely gonna the the 7s.
 
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