14 replies to this topic

[rexy]

Any tips?
I have tried brushing the tips clean and running sandpaper through the gap to give clean metal. The plugs never seem to behave particularly well despite best efforts.
Am I wasting my time? Are they stuffed once blackened?

[N/A-PWR]

Hello Rexy,

 

 My friend used a normal air gun small tip type sandblaster,

 

 and he just held the spark plug in his left hand with the spark plug electrode facing upwards to the side,

 

 and just simply wiggled his low pressure sandblaster in the right hand at the end of the spark plug.

 

Then he simply rotated the spark plug as he blasted, and puff's air in to aid as you go.

 

 

End result was a nice clean plug with no damage.

 

 

 

 

 

Edit:-

 

 I must say that he just did it in front of me in the workshop, no booth or anything like that,

 

 as you can imagine not much media would come out to clean a plug.

 

I would say the plug was clean in 4 seconds flat. 

 

 

 

If anything, it would be a sweep up on the floor of minimal debris. 

Edited by NA-PWR, 09 July 2016 - 08:53 PM.

[UCSLE]

Ive found the same with bike plugs, seems our quality modern fuels stuff them once there fouled.

 

had the same thing happen with my two stroke bike when it was fouling plugs , the only thing that would get them working was to clean down the side of the insulator  

[mick_in_oz]

Its not about the electrode being clean, its about the insulator being clean, the black deposit is carbon, carbon is conductive and shorts out the plug so it can not fire. As long as the insulator is clean the plug will fire.

 

Best way to clean is bead blast, as mentioned previously, you can blast down inside quite well, but its not that important, as once its firing, it should self clean once running and gotten to full operating temp.

 

Another reason for fouled plugs is too cold of heat range, the plug never gets hot enough to burn off the contaminants on the insulator, then..... fouled plug. The conventional wisdom is a hottie engine needs a cold plug, but really, unless detonation or some such thing is a problem that is being tuned for, you really should run as hot a heat range as is needed to keep the plugs clean.

[Ice]

Buy some NGKs

[jd lj]

I'd be hesitant about using media blasted plugs myself. If there's any of the abrasive media not cleaned out that could come out later I assume that it could damage the bore.

If the plugs are that bad just fit new ones and tune the engine to stop the problem reoccurring.

If you're in need of cleaning them to make do until you replace them you can use carby cleaner, a brush and compressed air.

[mick_in_oz]

Bead blasting plugs was standard practice years ago, and still is in the aviation industry, plugs used to be and still are serviced, blasted, inspected, gaped and then their ability to still produce a spark while under simulated cylinder pressure (compressed air).

 

Like with anything, do it properly and its fine, I've blasted literally hundreds of plugs and never any trouble.

 

It could be an almost new plug that's been fouled but an unlucky cold start, too much fuel, maybe the crab is a bit fat and it got a bit too wet and suddenly a fouled new plug, no way known i'd be putting it in the bin if it as new and only needed a clean, gone are the days of buying an NGK for less than $2. Actually, I'd still blast it if it was only $1, quicker than going and getting another one.

[71xu1]

Abrasive paper leaves a residue on the plugs, I wouldn't say you are wasting your time but as said getting to the root of the problem would be a good thing. I've always used a small file and then a cleanup with lacquer thinners, seems to fix the problem. I went up a heat range in my car and seemed to resolve my fouled plug problem.

Cheers Dave