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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Today I tore down my rear head and cylinder to replace the gaskets (bike is an 07 Sportster, EFI). 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.
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2007 XL1200C - Black Betty
Hammer Performance Impact A/C, CS 2.5 Slip-On, XiED, R6C 12" Apes, DK 2" tank lift w/ coil and ignition relocated, SG air shocks, Avon Cobra Whitewalls, laydown license plate, smoked signals, MoonsMC smoked LED taillight
Very normal from what we see day to day, here.
Scott
What would you recommend, Scott? Clean before reassembly, or reassembly and then some type of additive/detergent through the intake manifold while running? I want to fix this!
You are not SEEING what you are looking at.
The deal is under fire " load", etc the thing is all changing as you run.
You are looking at snapshot.
You can run it leaner......but holy pistons are too pretty to make compression.
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?
Here is a little trick that works well-
Mirror polish the tops, this will do a couple things -
1,- make it too smooth for stuff to stick to and just flakes off.
2, -It reflects the heat away back away from the piston and keeps it cooler.
The rest is all barroom arguments -but I always spend a couple hours on them and the heads.
I feel better knowing the parts all shiny smooth
Whilst there, smooth the seat inserts so there is nothing proud.
Unshroud valves if needed.
With all respect to Scott's view that the pictures are normal. However, considering 17K of those miles the breathers have vented externally, I suspect that the motor is using oil and running on the rich side. I think a compression and leak down tests are in order. JMHO.
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Carbon build up on pistons
