Andre: Another point of consideration if your Son in Law did indeed identify a wet (Gas Soaked) plug is that the gum or debris within the carb has not allowed the fuel inlet needle valve to close completely , which can cause an overrich condition. Usually unless you have a manual fuel shut off this wil cause a potential for flooding the oil within the crankcase fuel. In any case check you oil level and verify by smell if oil is gas contaminated . Woody : You scenerio sounds more likely coil or perhaps air gap issues perhaps due to corrosion. The popping could be a sign of a weak coil indeed. I would 1st rule out a bad plug wire or boot as you have indicated. Then confirm the other previous coil potential issues . Usually coils will so problems intially when engine has met warm up temperatures.

It is no "Old Wive's tale" at all. It isn't just the fact that the plug was "soaked in gas" that ruins it. It is rather something that happens to the insulator from running the engine in an in an extreme rich condition. The insulator gets a microscopic crack allowing the spark to jump through to ground. In other cases the rich condition forms heavy black carbon on the insulator thus conducting the spark to ground. This condition takes longer to happen. The first condition can happen in seconds or minutes. I have seen this happen personally many times on brand new engines. The plugs look perfect when removed but when tested with a pressure tester they will not fire. No amount of cleaning could ever make those plugs fire. The problem happened with multiple brands of engines and plugs. When in doubt...replace the plug. You cannnot judge a spark plug by looking at it every time.

Thanks for all the quick replies guys! I really appreciate all you've offered, but am still puzzled about some things. I'll try to explain below. Bill: Engine runs perfectly once a new plug is installed. Both cylinders fire, and the engine runs smoothly. Your response reminds me of the pre-takeoff procedure in an aircraft....checking both the left and right mags beore pouring on the power. I understand. Weak vs bad coil? Maybe? Head gasket leaking? That's why I loaned him my compression gauge on a hunch that he may be losing compression and getting incomplete combustion on that cylinder. Jim: I understand the dirty filter/choking effect. That's why I told him to spend a few bucks and get a new filter and pre-cleaner. But why would this affect only one of the two cylinders? One is running very clean and efficiently. Horse of course: No change in oil consumption. The fouling problem is definitely carbon, not oil fouling. I sincerely appreciate all your responses. I have a lot of past experience in small engine repair, but a long time ago and absolutely none with twins. With a single carb and a single intake manifold and filtering arrangement, I'm still puzzled as to why a twin would suffer plug fouling on only one side...unless it's a combustion issue, i.e., compression leak or some such thing. Again, thanks for your kind responses. After elaborating a bit on the problem here, I'd still greatly appreciate follow-ups if you can think of something new or not covered here. I'm out of ideas...except for the compression issue and possible head gasket leak. My friend may get back to me in the next day or two on what he finds with compression check. I'll let you know. Regards, Hal

We discussed this new plug design 3-4 yrs ago within the Tool shed forum . Response was cool . The pricing was outrageous at that time. I picked up a set for my lawnmower at the time White Equipt with 5.5 Briggs Quantum , also for my snowmobile since they were on sale at Canadian Tire at comparative pricing . They were still running fine after 3 seasons on both units with normal usage. I sold both units last yr and apparently they are still running fine , don't know if I would pay twice the price . I see numerous mower manufacturers offering E3 as original equipment so take it for what its worth . Normally OEM is fine with me . Perhaps others with actual experience rather than snake oil theories can assist you further.