I think she might be dead.....

[phatcat]

Was driving my gz the other day, doing about 30mph, when all of a sudden she went dead, and I heard a rattling noise. She wouldn't start back up, and still hasn't. I took out the spark plug, and the top is mangled. I switched it out for a new one, but she still wont even turn over, I'm just hearing a click from the relay, not a peep out of the starter motor. To make matters worse, the relay seems to have gone haywire now, holding in the ignition switch makes it click very rapidly, we're talking maybe six or seven times a second, were as it used to be just one click. So my question is, what could have caused the spark plug to get mangled like this? any ideas where I should start to fix this? or am I just better off getting a junked engine and switching them out? I'd like to hope that its just a simple problem, but something tells me I'm not in luck. have been running her on the motorway a fair bit recently, doing 60-65 for a good 6-7 km stretch every two days, so maybe that put too much of a strain on her. Here's a pic of what the plug looks like, any advice would be greatly appreciated.

thanks in advance,

phatcat :??:
http://s10.postimage.org/jigsrde2t/Photo0453.jpg (http://postimage.org/image/jigsrde2t/)

[blaine]

Hate to be the bearer of bad news,but that's melted aluminum deposits on the plug.The motor was badly over heated or ran low on oil.The engine is toast.Cheaper to get a replacement.Sorry.
:cry:

[phatcat]

Hate to be the bearer of bad news,but that's melted aluminum deposits on the plug.The motor was badly over heated or ran low on oil.The engine is toast.Cheaper to get a replacement.Sorry.
:cry:

Thanks Blaine but i think the pic is just bad quality its not a build up of surplus metal Its the actual threads of the plug that are torn out of shape. Its definately not aluminium build up I'd recognise that straight away I have experience welding aluminium it looks like it was just mashed by the piston or something. here's another pic quality is pretty much the same but slightly different angle sorry my camera phone is shit.

http://s10.postimage.org/qgmc6z3id/Photo0451.jpg (http://postimage.org/image/qgmc6z3id/)

[alantf]

Its the actual threads of the plug that are torn out of shape.

If that were so, then I think that you would have had a real problem getting the plug out. From the position of the central electrode, it definitely LOOKS like a build up of something.

[phatcat]

Its the actual threads of the plug that are torn out of shape.

If that were so, then I think that you would have had a real problem getting the plug out. From the position of the central electrode, it definitely LOOKS like a build up of something.

No its definately shredded by some kind of force I'm 100% certain its not a build up of any kind of excess metal the collar around the central electrode is mashed its not coated with anything. Once again I apologise for the photo quality. Here's a googled image that resembles what it looks like.
http://s17.postimage.org/6xm419qqj/102_1698.jpg (http://postimage.org/image/6xm419qqj/)

[Road_Clam]

have been running her on the motorway a fair bit recently, doing 60-65 for a good 6-7 km stretch every two days, so maybe that put too much of a strain on her.
http://s10.postimage.org/jigsrde2t/Photo0453.jpg (http://postimage.org/image/jigsrde2t/)

Here's a situational clue to what happened. Your engine ran heavily loaded, high rpm, long period of time.... and the final straw that broke the camel's back is you were somehow running a lean air/fuel mixture and or ignition detonation. Might have been dirt in the carb jets, and/or and air leak. I also bet you have melting, possibly a hole in the top of your piston.

Sounds like the GZ 250's might benefit from a one size richer main jet if you are going to be doing continued high rpm, high load driving on the highways...

[mrlmd1]

Is your engine locked up? Can you roll the bike with it in 4th or 5th gear?
What is the oil level in the site glass?
Did you check your battery voltage, it's not low so the starter won't engage?
Did you try and jump it with a good 12V battery, like from a non-running car?

You have more than one problem.

[alantf]

I'm no mechanic, but do you think it's possible that a valve has sheared off, dropped on top of the piston, then the plug's struck it.

I don't think we'll ever know, until the head comes off.

[raul10141964]

You may ned to machine the cylinder a new piston an probably a new head

[5th_bike]

I'm no mechanic, but do you think it's possible that a valve has sheared off, dropped on top of the piston, then the plug's struck it.

I don't think we'll ever know, until the head comes off.
That were my first thoughs too.

[clonak]

Seen it before, Definately something hit the spark plug, Possibly the piston, or as Alan said, something dropped into the cylander.
As to why it wont turn over, probably bent the piston/conrod so its jammed up. Or the conrod has snapped. Either way, head and cylander has to come off, Get the tools out and more pics.

[OldNTired]

I'm no mechanic, but do you think it's possible that a valve has sheared off, dropped on top of the piston, then the plug's struck it.

I don't think we'll ever know, until the head comes off.

Going by the pic, and his story of what happened, I'd say you are probably correct.
That central stem on the plug is pushed over, and the deformation around the edge
indicates that it was definitely taking a beating; the only thing that could
have done that is a valve.

[Water Warrior 2]

Looking at the pics and reading the comments I would say you are in for some exploratory wrenching. As suggested, you may as well pull off the head to investigate the condition of things. Wishful thinking and guessing will get you no where.
The riding season is over for many of us and we need some one to help and coach for a while.