[CrazyLegs]

our gemini cracks the porcelin inside the plug, above the electrode, this is being done during startup or shut off.  We let it idle down, then shut off with key.

 

[paul yarek]

crazylegs,
 what are you trying to say there pal ?

 

[98xc700]

Paul, I was wondering the same thing.

 

[CrazyLegs]

the porcelain surrounding the wire that carries the spark .....this porcelain cracks up inside the threaded part of the spark plug and therefore sparks against the side of the threaded area of the plug instead of at the little metal end of spark plug where it is suppose to.

 

[polarisxlt]

crazylegs > Help us out here there are alot of smart people here who would share there opinions but I'm not sure of what you are saying here?

1. What type of plugs are you using?
2. Have you tried new plugs or is this just one set that did this?
3. Is the electrode being damaged also,ie..... wrong length plug and the piston is hitting it?
4. Are you using it for any period of time and getting them extremely hot or do you put plugs in it and it just cracks them?
  Im no engine guru but if you give them some more detail I'm sure they will try to help!

 

[CrazyLegs]

we are presently using BR8es plugs which the manual calls for, yes we have tried more plugs, no the electrode isn't being damaged, no we don't use it for a long period of time, one small 5 minute run then shutting it off can do it, can't start it again because of damaged plug.  We also know of a KDX 80 motorbike that did exactly the same thing.  Would ratio mix of fuel have anything to do with it?  Thanks

 

[sledhead8923]

is it possible you may be putting them in to tight?
just a thought...

 

[michahicks]

OK, you have my curiosity factor way up there on this one. Can't say as I've heard of this one before. First thing I'm wondering is if heat is doing the damage or is something physical? Color of the porcelan should tell the story, but you don't mention it. What color is it? Is the machine knocking when running? If not, how does it run? Are you able to drive it normally? What is your throttle response like? Is it sluggish or responsive? Are you blowing smoke everywhere? Does it idle normally without stalling? Is this a single or a twin? Will you describe what you are doing from the time you start it till you shut it down and discover it won't start (are you screaming across a lake after carefully warming it up or putting around in the back yard, what)? Is the porcelan actually breaking away
from the electrode?

AL

 

[99Indy500]

Thats weird good luck!

 

[SNORAT]

Are you sure it is cracked? Can you see it? It would be pretty hard to see up in the plug were you are describing. I think the sled is getting flooded or loaded up and the spark current is following along the electrode down the porcelin till it jumps across to the base since spark current will follow a path of the least resistance. I would start with a good tune up and get the carbs checked for bad needles and seats,because I think your problem is you are getting toomuch fuel and it is loading up.