My 2010 Street Glide is a stage II 103. If I fill the oil when I change it (four quarts) I get mist out of the air cleaner and it ends up spotting the batter cover and bag on the right side of the engine much like your picture when I run it hard. The solution for me has been to run the oil level between 1/2 and 3/4 of a quart low. Even though when it was apart to do the 103 work, the head drains were modded to improve drain capability, if the oil level is high, I get misting out the air filter when I run the bike hard. In my case I can pretty much guarantee the misting isn't related to ring seal, the bike leak tests at 1 to 2 percent.

 

I've read all the information out there relative to oil level and breather blow-by to the air cleaner. Many of you swear that the oil level makes a difference but no one has ever explained a rational for why. Can you?

Personally, I just don't get it. What does a 1/2 qt. difference in oil level have to do with the volume of oil getting to the heads? As long as the pan/tank doesn't run dry the volume of oil to the heads should remain the same, and if the volume of oil to the heads is the same then why would more oil make it through the breathers, regardless of the oil level in the pan/tank?

Can anyone provide a credible rational to why the oil level has an effect on blow-by and oil in the air filter? I just don't see it, but I'm open to learning something from your explanations.

 

I would say that makes for a good break-in!! lol

 

Got my bike in February. Had 3 miles in it. Followed the break in easy for the first 500 miles. My dealer said take her easy for the first 500 then go ahead and ride it. From all that I have heard and read. The first 100 miles are key. I cant imagine 70 mph @ highway speed for 20 minutes after 500 miles would cause harm? I am just an owner though I'm not a mechanic.

I'm calling first thing to tomorrow. I'm sure it will be a few days before I will be able to get it in for service but I will keep you all posted on what I find out.

T

 

One more suggestion. Are sure it's coming out of the air cleaner? Check where it mounts to the head also - just in case they didn't get the o-ring right and sealed properly.

 

Understanding Blowby in Motorcycle Engines
If you ride your motorcycle too gently early on, you may never get the piston rings seated. Then Bad Things happen...like blowby and oil where it doesn't belong. From the April 2005 issue of Motorcycle Cruiser magazine. Read on for the causes from the February, 2009 issue of Motorcycle Cruiser


Every now and then I receive an e-mail from someone wondering why he's suddenly finding large puddles of engine oil in his air filter. While some oil misting in the air filter is normal and nothing to worry about, these guys, who invariably own large-displacement, high-mileage V-twins, are talking about a regular Exxon-Valdez, enough to make a real mess and require topping off the oil supply on a regular basis. Because this is an area of general interest, let's discuss what's happening.

By nature, all four-stroke engines require ventilated crankcases. The reason is twofold. First, when an engine is started or run at low temperatures, condensation takes place and fuel vapors migrate into the crankcase. These contaminants, essentially water and raw gasoline, mix with the oil to form engine-damaging sludge. Fortunately, once the engine reaches operating temperature the water turns to steam and the fuel remnants percolate out of the oil. As long as the crankcase is vented, either by the atmosphere or by using a positive-pressure system, these nasty byproducts are free to drift out of the engine and go their merry way without causing any harm.

The second reason the crankcase needs a vent is because no matter how hard we try, there is no practical way to eliminate air from entering it. Anytime the engine isn't running, atmospheric pressure pushes air into the engine through open valves or any other convenient entry point. When the engine is running, some combustion gases normally make their way past the rings to pressurize the crankcase as well. If the crankcase wasn't vented, pressure buildup would soon cause every seal in the engine to rupture as the trapped air sought a way out.

Originally, crankcase vents were nothing more than tubes connected to valves timed to open when crankcase pressure was too high and close when crankcase pressure was too low. This allowed the bad stuff to be forced out and prevented dirt from being drawn back in. A variation on this scheme vented the crankcase through a series of baffles, accomplishing the same thing with less complication. Although they were efficient, these breather-tube ventilators were little more than open pipes spewing engine contaminants directly into the atmosphere. As you can imagine, the EPA took a dim view of the situation and demanded that manufacturers, first car and later motorcycle, do something about it.

Although system details vary, one solution was to plumb the breather into the air cleaner. The fumes coming from the crankcase are then recirculated back into the engine and burnt.

Here's how the oil ends up in the air cleaner. Crankcases can only contain a given volume of air and its attendant pressure. Once that pressure is exceeded, you've got problems.

What causes excess crankcase pressure? Excellent question, grasshopper. For starters, anything that can reduce the crankcase volume, such as overfilling it with oil, creates problems, as will a restricted or damaged breather system. In V-twins, crankcase pressure sees rapid fluctuations, decreasing as the pistons rise in unison, then increasing sharply as they descend, compressing the gases in the crancase. But the most common culprit is usually something called blowby.

Blowby occurs when the piston rings fail to do their job properly. They may be worn or they may never have seated properly in the first place. This failure to seath the rings tends to be somewhat common is large-displacement V-twins. That is partially because they make good power down at low rpm and small throttle openings. However, it takes large throttle openings and high rpm to get the rings seated. If you went through those first few hundred miles without ever holding the throttle open or revving to the power peak—or only did it once or twice—your rings probably never seated.

The bottom line is that the piston rings can no longer effectively seal the combustion chamber. Combustion gases are leaking past them, pressurizing the crankcase. This creates all kinds of problems; seals leak, gaskets fail and, because the pistons are forced to compress the excess air on the downstroke, horsepower is lost. But these things don't happen right away.

Because the hot oil in the crankcase is easily displaced by the increased pressure and because it has a perfect path out of the crankcase via the breather, the first sign of impending trouble is nearly always oil migrating into the air filter.

Once the oil is pushed into the air cleaner, much of it condenses and drops out of the airstream, making a mess in the process. If this was the only problem it'd be bad enough. Unfortunately, some of the oil is pulled back into the engine along with the vapor and burnt, where it does more damage by glazing the cylinder walls and creating carbon deposits in the combustion chamber. At this stage the engine is on a downward spiral. It's only a matter of time before you'll be doing a top-end job.

I'd be remiss if I didn't mention that some engine designs are more likely to experience top-end sealing problems and/or breathing issues than others. In particular, large-bore twins, V or otherwise, tend to push more oil than an equivalent-displacement multi. This is simply because dinner-plate-size pistons moving through sewer-pipe-dimension bores are more difficult to seal and move greater volumes of air. As a side note, there are also some bikes with poorly designed breather systems, but that's a separate issue to be discussed another time.

Please don't get the mistaken impression that all large twins are just ring-eating monsters waiting to self-destruct; they aren't. Chances are the majority of us will never have a problem with blowby. But like they say, recognizing a problem is always the first step in curing it.

 

Yes, it's coming from just under the filter on the ventilator. Just went for a quick tool around and you can see the drips on the bottom of the filter. Got some drips the blew back on the batter cover and saddle bag. With all the great feedback now I'm starting to wonder if I have more of an issue than what I first thought?

I sure hope not but you guys a very good when it comes to questions and answers.

Thanks

T

 

Was the filter itself possibly over oiled?
Is your engine oil over filled or to the full mark when hot (right after shutting bike off)? If so, lower it by 1/4 quart and see what happens.
If these questions were asked above, sorry for the duplication.
If not, their are other issues causing it.

 

I did check the oil level and it seems to be right about perfect which is a good thing. The K&N came pre-oiled so I'm not sure on how much oil K&N puts in them but I would think by now 550 miles all of that would be gone? I've seen oil on the saddlebags and in the battery cover for a while but thought I was just picking up oils off the road and it was showing differently on the black denim. NOPE, I was wrong there! The oil seems to be coming from the back lower side of the filter. Right between the Ventilator Back Plate and the K&N Filter Element. After my short ride today it looks as the oil is now in the actual filter too where before it seemed to be coming from the seem between the plate and filter. I really hope it something simple like a o-ring but at this point I'm thinking that's wishful thinking.

T

 

The only time I ever had oil puking out the breathers on my bike was when the indy that did the top end and the dynotuning about a year ago also changed my oil . I went to his shop to observe some of the tuning. It was puking out a bunch of oil all over his dyno, I have my crankcase vented to the atmosphere, at that time breather lines straight down to the ground. I asked him wtf? He said it's not overfilled. I asked how much oil he put in. He replied "they hold 4qts". I asked "did you check the stick?" He said yes. I said well that thing is sick if it puking out that much oil. He said don't worry IF he may have overfilled it it will stop puking when it blows out the excess oil. So after he tunes it(that is another story) I take it home and check the oil, hot on the sidestand as per manual. It was way over full. i pulled out almost 1/2 qt to get it down to the full mark. I now have the breather line routed to a small catchcan so I can observe what is expelled. My bike does not blow oil when kept at the full mark.