Killing Spark Plugs

[Bad Monkey]

After my '96 Trident started running bad I pulled the plugs and found the #1 cylinder had burned the side electrode clean off. #2 and #3 were good. I figured it was a bad plug so I just replaced it. Acouple weeks and about 400 miles later the bike started running bad again so I pulled the plugs. #1 was in the same shape and as before #2 and #3 were good. So I switched the #1 and #3 coils and am running it to see what happens. Has anyone ecperienced this before?

[Lushy]

hey bad Monkey, i have not had that problem myself, but if i remember correctly a lean fuel condition can cause overheating of the spark plugs, this may lead to the ground electrode melting off.

[Bad Monkey]

Thanks for the input. If it turns out not to be the coils I'll pull the carbs clean em up and have them sync'd.

[sailfish]

I agree with the lean condition theory. A coil isn't going to get "hotter" and burn up a plug, coils and plug wires only get weaker. Look at the plugs again, before #1 burns up, and compare the colors. White is lean, tan is good, black is rich. There are web sites that describe plug colors.

A few other things to check:
Are the plugs the correct heat range?
When was the last time the valve clearances were checked?
Is the carb boot between the carb and the head tight and in good condition?
Are the fuel lines in good condition?

[Bad Monkey]

I pulled the plugs this morning and #1 is now a pretty tan and #3 is pretty gross however there are no signs of wear on the outside electrode. I sprayed down the carbs and am cleaning and re oiling the filter. Valves were done about 2500 miles ago. I agree with you about the coil getting weaker though. Is it possible that the plug became so fouled that the pressure just caused the electrode to break? I am just a parts changer so I am guessing. I will pay particular attention to making sure everything is properly afixed when putting it all back together as well. Thanks for your input sailfish. I appreciate all the advice I get.