fouled plug?

[joesawyers24]

My buddy who is a Harley mechanic. Keeps telling me that my plug is fouled. But its sparking with a nice crisp cracking sound. Does he even know what he is talking about?

 

[dirt bike dave]

IMO, yes, he does. When they get old, they will spark when you test them, but not run. When they get fouled, even if you clean them off, they won't work as well as a new plug.

 

[joesawyers24]

Thanks. I didnt understand that it would still have a spark.

 

[dirt bike dave]

I guess the conditions inside the cylinder are wetter, hotter and under higher pressure than what you have when you test the plug outside the cylinder. So what looks like a good spark just might not be strong enough.

Anyways, the spark plug is one of the easiest and cheapest things to replace, so it makes sense to have a few spares around just to rule that out.

In my experience, once they foul they either don't work ever again, or will foul very quickly from then on, no matter how much you clean them and how well they spark when you test them.

 

[mudpack]

I've cleaned fouled plugs that went on to live many happy lives. They have to be cleaned in a sparkplug cleaning machine, not with a wire brush....