Plug eating motorcycle? GS850L

[Mr.Mom]

Hi,
My bike seems to like eating spark plugs. There is one cylinder that has had 2 bad plugs in less than a week. I just got the bike and the cylinder had a bad plug so I put in a new NGK B8ES. The cylinder started miss firing after less than 100 miles on it. Bad plug again, simply no spark...?

What can cause plugs to go bad(lose spark)?

[Guest]

Hi,
My bike seems to like eating spark plugs. There is one cylinder that has had 2 bad plugs in less than a week. I just got the bike and the cylinder had a bad plug so I put in a new NGK B8ES. The cylinder started miss firing after less than 100 miles on it. Bad plug again, simply no spark...?

What can cause plugs to go bad(lose spark)?

Got a pic of the plugs that came out of that one cylinder?

[tkent02]

Lack of maintenance would be my first guess. Poor maintenance would be my second. Your PO likely didn't do any of it.

What have you done to it so far concerning routine stuff that should be done once in a while? Carburetors? Ignition? Valves? Burning oil? Air filters? The list goes on.

[Mr.Mom]

I'll be a little more specific. The brand new plugs lost electrical continuity with no signs of physical damage. There was a small amount of carbon.

[Guest]

I'll be a little more specific. The brand new plugs lost electrical continuity with no signs of physical damage. There was a small amount of carbon.

Still isn't telling us much.

[eil]

Plugs don't usually fail like that. How are you measuring continuity?

[Mr.Mom]

Plug it in and see if it sparks while touching the engine block.

[JTGS850GL]

How do you know it's not the spark plug boot or wire that's failing? Much more common then simply a bad plug. Have you tried the same "bad" plug on any other cylinder?

[Mr.Mom]

Moved the plugs & they didn't work in other sockets.

[Mr.Mom]

Flabbergasted another one bites the dust...

[Guest]

If that plug is fouling because of a problem with a carburetor, it can cause the plug to fail. Where's the picture of the plugs? Whatever you have going on seems to be consistent. Have your valves been adjusted and the carburetors rebuilt?

[Mr.Mom]

Carbon fouling in 50 miles? My phone camera sucks sorry.

[Steve]

Carbon fouling in 50 miles? My phone camera sucks sorry.

With dirty, poorly-adjusted carbs, I have seen new plugs look like that in 50 SECONDS.

.

[JTGS850GL]

Even out of focus I can see that those plugs look fouled. The shine makes me think it's oil fouled but it could be carbon fouled with raw gas causing it to look shiny. Like Steve said... Poorly adjusted carbs or ones that are simply dumping raw gas into the cylinder will foul a plug in just a few seconds.

[Mr.Mom]

Thanks for the info. I found a little bit of gas in my vacuum line. I am checking into the petcock as the extra gas culprit.