Scarlet is Dead!

[GLoweVA]

Well I killed her.
So, I've been having this issue about compression and I thought it was a head gasket problem, so I had a new one delivered Sat, but worked all weekend long, so I didn't get a chance to put it in yet.
I was on my way to work on Monday (28F) and I guess I pushed her a little hard.
She bogged down and died, there was oil and exhuast leaking out from the head. I limped it back home.
Here's what it looked like in the light.

You can see the oil streaks down the header pipes.
I checked the compression and got: 60/30/75/10
I pulled the carb out and saw this:

You can see the oily foam in each throat.
That didn't give me any good feelings.
I got the head off and saw a few bad things.
First I saw the bad area of the gasket between 1 & 2:

Then I saw the hole in #2:

Whoa! I saw another hole in #4:

That's two holes in # 2 & #4.

So, I decided to resurrect the Green Monster.

I used the new head gasket and took the head & carbs that was on the SG (G’s original head and carbs) and put them back on him and had to bring the coils over and a few other electrical items and then the fairing.
I got all this done in about 6 hours this afternoon.

[conquest87tsi]

Sorry to hear about your holey pistons man. It's interesting to see the apparent hot spot is the casting marks at the center of the pistons.

[DGXSER]

Having a blessed bike is never a bad thing, but yours is little to holy!

Well, at least you have a fun project ahead of you.

[Petersg_99]

It seems unlikely that all 3 things (blown head gasket, and holing two pistons) happened at the same time. Obviously the head gasket was last, but I wonder how long the holes had been there.

[GLoweVA]

The head gasket went first, then the holes came later as I limped it home (15miles).
The compression numbers were low for #1 & 2 due to the bad gasket, so when I had the failure on the interstate Monday morning, I assumed that the gasket finally gave out. (the oil and exhaust leaking out helped convince me of that.)

I do have 3 'extra' (used) pistons on my shelf from my first holey piston I replace on my G 3 years ago.

All I got to do now is get a set of rings and another new head gasket for the SG and about a weekend of nicer weather to work on her.

I hate having a carport.

I will be going and getting a ring compressor for this job and I will be replacing the lower base gasket too. (something I wish I had done on the G 3 years ago when I did that one, since then, it leaks just enough to be annoying.)

No I'll have 3 holey piston paperweights !

[LoHo]

I was wondering what the mechanism is for holing a piston. Is it a lack of oil allowing the piston to overheat, or a combustion issue, or some inherent trait of the piston?

[LoHo]

By the way, it sounds like Scarlet is down, but not out. Dead might be an overstatement. Let me work on it and I'll make sure she's dead.

[GLoweVA]

I was wondering what the mechanism is for holing a piston. Is it a lack of oil allowing the piston to overheat, or a combustion issue, or some inherent trait of the piston?

I've come to the conclusion that in both of my cases, it was a way too lean condition and running it too hard for too long. Thus it melted.

In other words, if it feels like it's only running on 2 or 3 cylinders, then don't try to get her very far and definitely don't push her too hard trying to get there.

(Wow re-reading that last sentence can really be construded differently in a different context. )

[GLoweVA]

Yeah LoHo, she's not really 'dead', but it sure felt like it yesterday when I saw those holes.

I'm starting my shopping list for the parts I need. The most expensive ones are gonna be 4 sets of rings and the new head gasket.

A friend of mine at work asked me about maybe thinking about a bigger bore....

Maybe a Wiseco kit maybe the way to go instead....

[DGXSER]

then don't try to get her very far and definitely don't push her too hard trying to get there.

(Wow re-reading that last sentence can really be construded differently in a different context. )

Especially when you add the context of the discussion is about holing your pistons.

[crazy steve]

I've come to the conclusion that in both of my cases, it was a way too lean condition and running it too hard for too long. Thus it melted...

Yep, running lean and hard will do this every time. Lean can make more power, but too lean leads to 'death smoke' i.e. white smoke which is vaporized aluminum going out the exhaust...

Good example is the NHRA fuel cars; when you see a cloud of white smoke out of one of those, that's the piston tops evaporating...

[LoHo]

I had forgotten about lean mixture and the high heat that results. And I guess the middle of the piston is the place for that heat to focus, as it is the hardest place from which to drain off some heat.

My bike was set up rich for a very long time and ran fine. In my current troubles, I changed my carbs to the spec float height, hoping for better running and better MPG, but fear of a lean burn-up is haunting me. I guess I'll deal with that when/if she gets running again.

[LoHo]

Some wiser than I have posted here that our XS1100s like to run on the rich side. Is that an engineering fact, or a way to avoid burning the engines up in exchange for reduced MPG?

[GLoweVA]

I had forgotten about lean mixture and the high heat that results. And I guess the middle of the piston is the place for that heat to focus, as it is the hardest place from which to drain off some heat.

My bike was set up rich for a very long time and ran fine. In my current troubles, I changed my carbs to the spec float height, hoping for better running and better MPG, but fear of a lean burn-up is haunting me. I guess I'll deal with that when/if she gets running again.

Your biggest indicator of being too lean will be your plug color. Check them often.

Edit: I would think that if all 4 were running at the same leaness then they'd be balanced and the heat wouldn't be an issue.
In my cases it was one (or 2) that was driving the bike instead of all 4 providing power and the double work load caused the higher heat.

[motoman]

I had forgotten about lean mixture and the high heat that results. And I guess the middle of the piston is the place for that heat to focus, as it is the hardest place from which to drain off some heat.

My bike was set up rich for a very long time and ran fine. In my current troubles, I changed my carbs to the spec float height, hoping for better running and better MPG, but fear of a lean burn-up is haunting me. I guess I'll deal with that when/if she gets running again.

Actually that hole is the center most point and hottest point of ignition. Just goes to show that the 4angle head chamber cuts allow firing at the center most point, resulting in a hemispherical combustion point, just like the Yammy engineers intended AND claimed. Ignition mimmicks a true hemi motor without the spark plug being central located above piston.