I also posted this over in the engine section, but I thought I'd ask over here too since it seems to get a bit more traffic.

I have an 08 Street Glide with just under 49,000 on it. For the last couple of years I've had the annoying misting every so often of oil from the A/C. I'd go thru the process of wiping it down, taking the filter off and cleaning it and then rinse, repeat.

So this year when I did the extended bags and rear fender, I decided to do the breather by-pass to avoid having to wipe down the new bag. Now I realize that this only addresses the symptoms and not the route cause of the oil coming out the breather tubes. I was also planning on replacing the breather assemblies when I do cams sometime this year and also drill out the breather drains along with upgrading the oil pump to increase scavenging in hopes of eliminating the problem.

I also was toying with the idea of adding a 103 BB kit, if for no other reason than to have fresh new pistons instead of what mine probably looked like from all those years of the blow by being routed back into the engine.

Which led me to get an endoscope and take a few pics inside each cylinder to see what was going on. I quite honestly expected to see more carbon build up than I did, but I'm pretty sure around the edges it's a sign of oil seeping past the rings.

I'd love to hear some opinions and insight on what some of you may be able to see in the photos

Thanks

 

Do you get it out on the highway up to a good speed on a regular basis? Tell us a little more about your 49,000 miles and the norms. What RPM range do you tend to ride in?
You might should consider a compression test for more info...

 

I actually took some pics of my pistons also on my 2013 FLHTK with approx. 43K and they looked very similar, but the carbon wasn't as thick.

 

I ride it to work a fair amount of time and that has a pretty good stretch of highway (running 70-80) it's about a 50 mile round trip. I usually ride in that 2000 to 3000 range most of the time, and try to keep it in the "sweet spot" of the power band . With cruise set to 72mph I'm turning around 2700rpm's. Occasionally I'll open her up just to clean out the cobwebs, but by no means am I treating it like a sport bike.

Quite honestly she runs good. Could it be better? Yeah, I'd like to have a little more roll on power (hence the cams sometime soon) and I think I should get better than the mid to low 30's in MPG it tends to run. Other than that it been a great bike, no complaints.

 

First...I edited my first response to include pics.


I get great power and good to exceptional MPG. Average 38-40 and have gotten a couple of 58 and 60 MPG tanks. I was still getting some minor pinging and wondered about carbon buildup, so took the pics.


I have complete stage 1 on my factory 103. Air cleaner, pipes, tuner and cat removed from head pipe. I have since those pics used some upper engine cleaner/decarbon in the fuel. If I remember I will take new pics of cylinders in next couple of days.

 

The carbon can cause detonation. And it looks like oil consumption causing the carbon buildup. For the record a compression test tells you if you engine is really bad but won't give you much info other than that. You need to get the majority of your final reading in the first compression stroke. Crank it 15 times to get a good number or 6 times to get the same reading.....both give the same end number but a very different prognosis. A leakdown test is the best and easy to do. If you're getting double digit numbers your engine isn't as good as it should be.

 

The carbon buildup caused by oil could also come from oil ingestion through the air cleaner VIA the crankcase breather.