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Today I tore down my rear head and cylinder to replace the gaskets. I've had a minimally leaky head gasket on the rear head for approximately 6-7k miles; so, I decided I would fix it while my front end is in the shop for powder coat.
This bike only has 17k miles on it and I've had the air cleaner venting to the atmosphere for almost 10k miles; before that, it was using the stock air cleaner system that vents back into the intake. When I took the jug off the piston, this is what I found. I was shocked. The carbon build up is scaly and flaky. Surely this can't be normal. Am I wrong? I'm almost afraid to put everything back together with the way the piston looks. The carbon build up is scaly and flaky. Is it flaky because it's being broken down by detergents in the gasoline and finally getting clean air instead of oily, hot air? This is my first tear down and I'm not sure what the pistons looked like prior to this point in their lives.
I've also included pics of the intake manifold and the valve chambers. I assume these are gunky because of the 7k miles this bike endured with oily air being filtered back into the intake.
With those that are accustomed to tear downs and rebuilds, what would your opinion be on the best method of action? I've heard of Seafoam, misting water into the intake, etc. Just wondering how I should approach the situation. Thank you in advance.
By having a leak that could be from outside to inside the mixture has surely been affected?
It looks like you need to give everything a very good clean and check the valve seats for burning. You might need to use some grinding paste on them. Use something that doesn't leave scratch marks in the piston.
If you hadn't had the leak one would suppose it has been running very rich.
Last edited by Andy from Sandy; Jul 17, 2018 at 02:26 AM.
Thanks for the input. I know that the piston tops won't be spotless due to the nature of the beast, but it sure is unnerving to find that much gunk in your heads.
I'm also including a picture of my plugs to aid in further analysis of the combustion chamber(s). Does the condition of the plugs point to anything in particular?
Did both pistons look like that or just the one with head gasket leak?
Not sure about the front piston. I only tore down the rear head because that was the one with the leak. I would assume the front looks at least somewhat similar to the rear due to the fact that the intake port on the front head is just as gunky as the rear head. Unfortunately I don't have a bore cam to confirm.
I think that oil inside the cylinder combustion chamber would've caused a noticeable amount of smoke coming out of the exhaust, no?
I would think so too. But I may be wrong. Either way, I have had zero smoke from this bike.
Originally Posted by xFreebirdx
This, plain and simple.
I will have to try the water infusion method when cleaning the pistons. Here is what I was ble to accomplish with a razor blade, some carb cleaner, and some patience. Please note that I made sure to block off the bottom end cavity by covering it with a piece of cut-to-fit cardboard and a grocery bag. Much better now. Makes me wish I had my other jug off the bike...
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Carbon build up on pistons - problems?
