I am wondering if anyone has ever heard of that? The spark plug really did melt, and so did the head. I will attach some photos of it. I found it to be amazing! I was out on the ice, and all a sudden it started hissing like mad. I got it back to my garage and took 'er apart and found the spark plug to be melted into the head. I had to take a wrench and a hammer to break it loose. Any body?

Aluminum will melt at 1200-1300 degrees F. Steel on the other hand (the plug) doesn't melt until almost 3000 degrees F. IOW the aluminum would go long before the plug most likely. Are you sure you aren't seeing a peening issue instead? If you broke off a biece of ring and it peened the head and plug, it might look deformed as if melted perhaps.

What would have caused that? Could it be no oil, (2-cycle of course) or did not let the sled warm up enough before heading out.

I'm curious too.

richard

Aluminum will melt at 1200-1300 degrees F. Steel on the other hand (the plug) doesn't melt until almost 3000 degrees F. IOW the aluminum would go long before the plug most likely. Are you sure you aren't seeing a peening issue instead? If you broke off a biece of ring and it peened the head and plug, it might look deformed as if melted perhaps.[/b]

No it really did melt. Sorry I didn't get around to posting those pictures. What is Peening? And there was a full tank of 2-cycle oil in the resovior too. And I ran it around the lake at 15-20 tops to warm her up. The spark plug melted also.

Due to the non-similar melting points, your cylinder head likely would have turned into a puddle long before the steel on the plug could have melted.

Well, if what you mean is that the top of the piston melted and the liquid aluminum cooled around the spark plug, I have seen that.

If it was the first ride of the season, the most likely reason was a partially plugged main jet. green gunk forms in the jet and causes the cylinder to run too lean. One of the symptoms of this is the sled will seem to run better than it ever has.....until it blows up.

If it was the first ride of the season, the most likely reason was a partially plugged main jet. green gunk forms in the jet and causes the cylinder to run too lean. One of the symptoms of this is the sled will seem to run better than it ever has.....until it blows up.
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Now that my friends, is good to know.

Richard

If the cause was a main jet, you should have been going a lot more than 15-20 miles per hour. The 440 should be able to get between 50 and 70 mph when the engine is depending on the main jet.

If the engine is running lean and having overheating/ metal melting issues as a result, typically the piston crown will show it before other parts simply because the piston is less able to rid itself of heat. I would doubt a lean condition if there are no signs on the piston.

The only thing I can thing of that might allow a plug to get very hot would be the use of a wrong heat range plug (by several numbers). Even that however should not overheat the head (since the very reason a plug overheats is that it isn't conducting heat into the head well. Perhaps a hot plug loosely installed could overheat in such a manner.

I just wanna see the pics.... :lookaround:

Were the plugs tight in the cylinder when you removed them?
A typical spark plug dissipates about 60 percent of its heat through its threaded contacts. If the plug is loose, not only does the plug run overly hot, but the air leaking into the cylinder causes a lean A/F ratio in the combustion chamber. The two problems typically combine to raise cylinder temps high enough to pop holes in pistons, but if you caught it just before it holed the pistons you may have just noticed it as melted parts. Normally the aluminum from the head and piston melt and ball up in the end of the spark plug and sometimes the heat is enough to burn the bottom electrode off the plug.

Just a thought,

[attachment=41820:Picture1.jpg]

Sorry Guy's just got a snowfall this last week, been out riding. But here's those pictures I promised you's. Its under Arctic Cat. [url="http://www.freewebs.com/bstthomas/"] :thumbsup: I know the last one is kinda fuzzy but its the head.

By the way, the piston wasn't scored, nor was the cylinder walls. There wasn't excessive play with in the cylinder walls and the piston. I usally run it for quite some time to warm it up. Once i have her warmed up, I cruise around 45-50 on the trails. There was oil all spewed over the top of the head. Although the other head was scored as if the tip of the spark plug snapped off and was jumping around and putting nicks in the head, but not the piston. I think my sled is haunted or jyxed. It does some funky crap! It like to walk away from me, stop for no odd reason and won't start back up. it eats recoil ropes. Speedometer stop working and then come back on. Dashlights come on and off. Hand warmers come and go....I swear it's haunted! LOL...any Idea's though?

WOW
That plug is surely melted.... If you ever find the cause for this let us know... I've never seen anything like that before.
As for the sled doing all those wierd things... it sounds like she is haunted. :lol:
If it were me...I would think about retiring the haunted machine to a parts sled and go find yourself another one like it. Then again be cautious of what parts from the haunted sled go on the new one... wouldn't wanna carry the jinx over to that sled. :confused:
Have any pics of the pistons, inside shot of head, better shot of plug hole in head, etc... Plug was clear to see but couldn't get anything out of the head shot.

I would think the only way it could get that hot was if the plug was loose or damaged and was letting the cylinder vent exhaust gas and inhale fresh air , leaning out the mixture and causeing it to super heat the plug.

Sounds like you machine needs some attention. Find the break in you electrical system and correct or repair it. Make sure your speedo cable is well and properly attached. (If you install the cable backwards it is possible for the cable to "sink" down inside the sheath. There is a small ferrule attached to one end of the cable itself which will prevent the cable from dropping down. That could be your problem.)

As for the plug, it seems clear that hot gases from some source have "washed" that portion of the plug away. I have had or seen plugs come loose on several occasions, but never seen that or anything even close to that. Yes, the plugs will be hot. However, the heat is usually evident on the electrodes as well. Yours look perfect.

While it is true that gas cutting - super hot gases being blown past something- can cause some issues like that, the damage to the aluminum head should be at least as much and probably a lot greater than that.

I'd like to see what the head looks like from the inside. It seems clear that your engine was not overheating, at least not in a serious way. Your electrodes show no sign of being excessively hot. Were the plugs threads in that head in good shape before this happened or had they been crossthreaded at some point?

It is a rather unusual deal. Normally if an engine runs with a plug loose, you'd push the load to the other cylinder since the one with a loose plug tends to be running on lower compression - which won't be an overheat deal. As the plug works its way out, the electrodes also tend to "disappear" into the hole so the spark is not quite as effective in igniting the fuel, which I would assume might retard the burn on that cylinder just a bit, again a cooler effect.

Gas cutting is the only possible explanation I can muster.

Looking at those pics of the plugs, and the description of dash lights blinking on and off, and the sled shutting down for no reason, makes me wonder if there is something electrical going wrong. ie. a short to ground ?. notice the melt pattern on the plug seems to be facing the open part of the electrode at the end of the plug. Short circuit voltage is very high , and will cause melting of hard or soft metal ( I once blew the end off my linesmen plyers when I accidently touched a 480 volt lug, and a grounded breaker panel.) Is it possible that un regulated voltage could have melted that plug and caused secondary melting of the head acting like an arc welder ? what if the plug did come loose and the electrode made contact with the head? Sled would shut down?? hmmm. Just looking from the out side in : :lookaround:

Alright, I got the speedo to work again. As for the dash, thats a ghost story I guess I took and checked all the connectors and the wires to see if the mice had a "Hay-day" with them. I am trying to upload some more pictures of the head to my site, but its not working out. I try again tommarrow. I got it all back together, otherwise I would snap some shots of the pistons, and piston walls.

I have seen the electrode melt before.... Its cause is super lean conditions.

I have seen the electrode melt before.... Its cause is super lean conditions.[/b]
The electrode didn't melt. It was the outside, threaded part of the plug that melted. I think he said the pistons and cyl were fine...which they wouldn't be if it was a lean condition.....