A Hypothetical . . .

[GLoweVA]

The way I see it, those 2 were working twice as hard to provide the same amount of power trying to keep me at speed, in other words, I was about twice the throttle amount needed with 4 running than with 2, so it was working really hard and not having a chance to cool down.
And yeah I was almost WOT most of the time, so those 2 got a lot of fuel and heat and I think I was also a gear down from where I normally would have been, so the rpms were up a little more than normal too.

Had I been running 120 mains instead of 110s, maybe it wouldn't have done it.
Not something I want to try to see if I can replicate.
#2 (you can see the head gasket damage between #1 & 2)

#4

[WMarshy]

Wow, you were pushing it hard trying to maintain 40 mph with just 2 cylinders. No wonder they gave out.
I can say from experience that I have limped my bike home on 2 cylinders some 5 miles or so and had no adverse affects. My situation was a little different because I was not getting spark but was still getting fuel...

It shouldnt hurt it if all you are doing is putting along trying to make it to the next pull off. Pushing it WOT on 2 cylinders will likely damage something as already proven. Why the center of the pistons? Because thats where they are the thinnest and get all the heat. Wouldnt have mattered if you were one jet size larger or not (IMO)...

[ViperRon]

Well I do not know for sure what the actual reason for the pistons melting in the bike but I had an instance where on a 4 cylinder truck the center part between the 2 center cylinders on the head cracked. At first it missed and poor power. I drove it 80 miles home but on the last few miles I had to cut it off frequently cause the rubber and plastic under the hood were getting really hot. The paint on the hood was bubbling some. The heat was due to it had burnt out the head gasket so bad water was pouring in so it was more steam engine by then. When I pulled the head it had serious burn marks where the cracks were and nearly all the head gasket was gone and one cylinder was all that was left intact from the head area. Now on this trip I'd only get about 10 miles till I'd have to feed it 5 to 10 gallons of water but the last few it had boiled out and any water would have just cracked everything.

Now the head was destroyed melted even in cracked areas but the pistons are still running fine in the same truck with about 80,000 more miles on the 220,000 it had when it had the issue. No marks on the pistons. Now if heat would melt a piston I think this would do it.

Now I have seen engines with melted pistons that had other additives added to the fuel. And many times I have seen nitros melt them.

I have seen a piston melt in a car only from one thing the valve guides were bad it burnt oil and built up bad carbon and you could hear the intermittant knock. Compression was thew the roof no open space. Well eventually it cracked the piston and in no time at all burnt a dime size hole and melted the entire top of the piston.