My 09 Fat Bob doesn't have this issue but my 2010 Ultra does. Ultra did it from new with stock filter and with Stage 1. Even low oil level doesn't stop it. Stealer answer was some bikes do that. Went with Krank Vents for Buell and Special Applications. Ran hose from them to catch can. Glad I did because you see what all is sucked into intake and goes to engine. Harley big wig was here last weekend and gave him an earful. Showed him what I had to do to stop oil from dripping from air cleaner.

 

Ok I will.

Regardless of the actual crankcase pressure, whether negative or positive, high pressure leaking past the rings from the combustion chamber will increase the crankcase pressure. Whether or not this increase is the cause of the oil carry over to the air cleaner is debatable, but nevertheless, the increase in crankcase pressure will exist.

 

OK, I can always learn. Thought about it some more and I was just considering the compression stroke and didn't think about the power stroke. That would be a whole new ball of wax and I can see how the compression stoke would increase crank case pressure.

 

The biggest issue affecting oil carry over with the V-Twin is inherent in its design with the cylinder arrangement (45 deg) and the single crankpin. Even though we're talking about the effects of blow-by here, blow-by (unless really excessive) is not the primary cause of oil carry over. It's the engine design. The only way too fix it would be a complete redesign of the HD powerplants and that would be contrary to what we all love about HD.

In the current V-Twin, with the cylinders being 45 degrees offset, both pistons are moving upward and downward at the same time during a portion of the engine cycle. This creates high and low pressures in the crankcase and this is the problem the breathers have to overcome. It's a difficult task.

In other engine configurations, let's use an inline four cylinder as an example, two pistons are moving up while the other two pistons are moving down. The pistons moving in opposite directions tend to offset the pressure variations in the crankcase. You don't get this offsetting effect in the V-Twin.

This oil carry over issue is a complicated one and as long as we have V-Twins with the current cylinder and crankpin arrangements, some engines will continue to exhibit this problem.

 

I just noticed oil coming out of my k/n air filter. I only have 1500 miles on my 2011 SG. I have never noticed this oil before and its now all over bottom of filter, and its not just dripping, but even up higher on top of my rear cam. Like its almost spraying?? Why would it just start doing this? Any suggestions or thoughts? I'm headed 500 miles to sturgis in 4 days and sure don't need any engine issues.

Thanks for any help! It's sure appreciated!

 

bugs.....don't think you will have an engine issue but running at high speeds for a long period don't help the issue. I used the copper tubing mod and it worked well. Its shown on one of the other pages of this thread. Its just the nature of the Harley beast...Have a good trip!

 

ok...thanks for input! I realize there are a ton of threads on this subject. I guess I was just concerned because its a newer bike and this just started happening. I'm wondering why it would just start doing this. My oil level is closer to full than half way...so thinking about taking some out. Just one of those things that bug me I guess! Annoying!

 

Thats not going to do much....many are experiencing it.

 

I tried 3 1/4 qts but didn't stop it completely. Did make it somewhat less but the copper tubing was one of the answers.

 

Take it to your dealer and have them get you fixed. They will have seen this in the past and be able to take care you of you.