Re: When spark plugs go bad
They ARE important--especially when you only have ONE...a single cylinder engine needs one that works,isn't fouled,and has no cracks in the porcelain to short the spark to ground instead of firing at the tip...you aint got 3,5,or 7 other cylinders to run on like a car when one dies--one dies,its DEAD!..
I've had plugs last decades,others I've had "die" suddenly,like a switch went off inside them,and though they'll spark outside of the engine fine,they would not let it start when put back in--tried a new one and VROOM,cured!!..I've had some plugs "shut down" after they get hot,then work again once they cooled down..(I smash those so I wonrt end up using them again !)..
I think some magnetos get flukey too though,and make the plug look "bad",but putting a new one in or reducing the gap on the old one can mask a weak magneto,as the new plug has lower resistance,and the smaller gap is easier to jump..