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Fouled Plug - Reuseable?


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02-06-15, 07:47 AM   #1  
Fouled Plug - Reuseable?

The carb on my dirt bike flooded and fouled the new spark plug I just put in. I pulled the plug and burned off the fuel with a match and now the ground electrode is covered in carbon. I tested the plug and it still has a spark. Should the plug be fine or should I replace it with a new one? They are $15 a piece, so I'd prefer to reuse it, but not if it's going to affect performance. It's an NGK IMR8C-9H iridium plug.

 
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02-06-15, 09:04 AM   #2  
I just run it over the wire wheel on my pedestal grinder, blow it out with compressor to make it look brand new.

 
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02-06-15, 09:13 AM   #3  
I know some say once a spark plug gets fouled it should be replaced but I've always cheaped out, cleaned and reused them. I've never had any problems as long as the plug was good previously.


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02-06-15, 09:36 AM   #4  
20 (?), maybe 30 years ago, it was common to clean and reuse spark plugs. In fact a lot of dealers, service facilities, etc. had spark plug cleaners. Basically a small sand blaster as I recall that you would thread the plug into, turn it on, and it would gently blast them clean. Other shops would simply use a wire brush, but it was common either way. Things change, and I doubt you could find a mechanic today who would do that. Nevertheless, I still clean and reuse them on things like lawn mowers, etc., as long as I cannot see any pitting in the metal.

 
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02-06-15, 10:02 AM   #5  
aka Pedro, I remember those sand blasters, in the shop but it was 40-45 years ago. Cleaning & re-gaping a plug works fine when it's just carbon fouled. It's better to replace it once unburned gas hits it even though it will still work. $15 is way too much for a spark plug.

 
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02-06-15, 10:05 AM   #6  
Cleaning an iridium plug is okay to do? I thought you weren't ever supposed to get near the electrode. In fact, they recommend using only a wire-type gauge to avoid damaging it. Would an alcohol swab be enough to at least clean the ground electrode?

 
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02-06-15, 10:14 AM   #7  
So what's the deal, Pulpo? You came along just to make me feel old? Just kidding, but yes, counting back, I think you're right. 40 or more years ago. No wonder that what hair I have left is white!

 
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02-06-15, 10:17 AM   #8  
It's the electrode that needs to be cleaned more than anything. If I didn't have the sand blaster, I would use a piece of emery cloth. I would still do that today. I don't see how alcohol helps a plug that was fouled with raw gas.

 
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02-06-15, 10:30 AM   #9  
I reuse plugs all the time. In aircraft it's far more common to clean, test and re-install used plugs than it is to put in new ones. There's even a little spark plug servicing box just for the task. Stick the plug in one hole and the tip gets bead blasted and in another location you can test the spark while the plug is under pressure. Important as it's easy to make a spark at ambient temperature but it becomes more difficult as the pressure increases.

 
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02-06-15, 11:19 AM   #10  
I still have the spark plug sand blaster I bought from JC Whitney some forty years ago. Haven't used it in probably a decade.

Mossman, I tried to send you a PM but your box is full.

 
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02-06-15, 01:16 PM   #11  
Mossman, I tried to send you a PM but your box is full.
Thanks for bringing that to my attention. It's empty now.

 
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02-06-15, 01:30 PM   #12  
Unless you are racing it, just clean it up and re use it. Autozone has them for about 1/3 less and you can check a comparison chart and get another brand cheaper.


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02-06-15, 01:35 PM   #13  
In fact a lot of dealers, service facilities, etc. had spark plug cleaners.
I used to have one it was pretty beat up when I got but I cleaned/painted it and used it for years It had a cloth bag that held the sand which finally disintegrated and I couldn't get a replacement or figure out how to make one so I wound up trashing it That was probably 25 yrs or so ago.

btw - y'all aren't making me feel old, I do a good job of that all by myself


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02-06-15, 03:22 PM   #14  
Pilot Dane, so I guess prop planes weren't included when they said that flying is safer than driving, if they clean plugs & don't replace them, in aircraft. I suppose that only applies to jets.

 
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02-06-15, 05:11 PM   #15  
Two and a half separate issues.

1. Spark plugs very, very rarely fail (unless you drop them). Cleaning and testing has proven effective for 60 years. They have no moving parts and they wear by very slowly eroding over time. Even when they are bad... they usually still work. So, their affect on safety is minimal except for the fact they are rarely the cause of an engine failure.

2. Piston powered aircraft have a much worse safety record than turbine powered aircraft and even I have to admit that certain types of flying are more dangerous than riding in a car. Part is due to crew training and professionalism. You rarely find a commercial airliner buzzing a lake to wave at girls in bikinis.

1/2. Turbines also have "spark" plugs. Something's gotta start the fire. During some phases of flight the ignitors are run continuously but they are off much of the time.

 
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02-06-15, 07:39 PM   #16  
I take a piece if sand paper and run it along the gap in both directions to clean the electrode and the underside of the tang or anode. Never had a failure. Used them till almost nothing is left of the electrode.

 
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02-09-15, 08:52 AM   #17  
Bike seems to be running fine with the previously fouled plug. Now if I can just figure out why it takes forever to get the bike started.

 
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02-09-15, 12:35 PM   #18  
How is the bike's power when it's running? If it's strong I'd assume the compression is probably good. You've got spark so that leaves fuel. I assume your bike is carbureted. Does it have a choke? Is that adjusted and working properly?

 
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02-10-15, 05:10 AM   #19  
Both the intake valves need shimming. One is at the lower end of spec and the other is out of spec. I'll be doing that this weekend. Hopefully that cures my cold start issue.

 
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02-17-15, 10:40 AM   #20  
I can't start to remember the number of sparkplugs I have cleaned and reused.
Times change and most people just replace sparkplugs. By the same rule, people today, just buy premixed liquids?
I learned in tech training, years ago, that even worn out --burned up sparkplugs can be "rebuilt"
I never use a motor mounted wire wheel and have used the mentioned plug sandblaster, But found that if you just hand clean with a wire brush, you are better off.
I was told that sandblasting wasn't good for the plug???
When investigating how a sparkplug works, the spark likes to jump from-- and to-- a sharp edge. With that being said, the center electrode needs to be filed flat as well as the ground electrode.
As far as cleaning with a match flame, I have never done that. Instead I use a small propane burner because that is much hotter.
Of course I am referring to standard sparkplugs, not some of the newer platinum type.
Many times it is just better to replace with a new sparkplug, but with todays foreign made plugs, you are gambling.
I have installed many new sparkplugs that were bad.
One thing I will not do is reuse a sparkplug that I know has been dropped, and that could very well be the problem with some of the new sparkplugs.

 
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02-18-15, 07:26 AM   #21  
I found a great deal on a 4-pack of plugs, so I'll pop a new one in just to be safe.

 
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