Ever have spark plug go bad??

[justopelt]

So I rebuilt my motor over the winter and got it running over that past couple of days. It was running perfect yesterday, then I went to start, it wouldn't start. If it did start was missing really bad. Went to check spark and one of the spark plugs had no spark. Changed it and now it runs perfect. But the plugs that were in there, I just put in last week. Any reason why that might happen to a brand new plug?

[Motofool]

Originally Posted by justopelt

..........Any reason why that might happen to a brand new plug?

Many years ago, new spark plugs that worked for a few hours in a two-stroke motorcycle engine were not uncommon.

Microscopic fractures in the insulator created a path to combustion gases first and then to ground for the high voltage.

http://www.madehow.com/Volume-1/Spar...#ixzz2yhdeS9zY

Quality control is much better now, but defective plugs can still make it out of the factory, I suppose.

[harvey58]

I am a small engine technician and often see spark plug issues.
First, are you using NGK plugs? Don't use anything else. Champions only work in Chryslers and lawnmowers, Autolite in Fords. The aftermarket plugs seem to only work when they want to. I have seen this happen in my daily experience. Take out the (incorrect) plug, replace it and I never have a complaint from the user again.
Second, is the carburetor flooding? This can be a difficult problem to diagnose.
Plug comes up wet after setting some period of time. Replace plug, bike starts and runs "fine" Next startup reveals same plug soaking issue. If that is the case, then look at the carbs.
I had an issue with this on my bike. Replaced the inlet needles and problem was solved. The needle tips appeared fine, the problem was with the dampening spring in the needle itself.
Hope this gets you riding SAFELY again!