Blow-back...
Harley Oil & LubricationDiscuss Blow-back... in the Harley Tech & Harley How-to forums; ...or blow-by. I can't remember what it's called, but I do remember what it means. It means oil is dripping out of your air cleaner.
So, I'm sure you've guessed ...
...or blow-by. I can't remember what it's called, but I do remember what it means. It means oil is dripping out of your air cleaner.
So, I'm sure you've guessed it. Oil is dripping out of my air cleaner. Here is where I, once again, show how green I am.
1. What can cause it?
2. Does it really hurt anything?
3. What can I do to address it?
The bike is still under warranty, so I don't mind taking it to the stealership, if it's necessary.
__________________ ===================== Rob 2007 FXDB San Diego, CA
John 1:14
It is the duty of nations, as well as of men, to own their dependence upon the overruling power of God, to confess their sins and transgressions, in humble sorrow, yet with assured hope that genuine repentance will lead to mercy and pardon; and to recognize the sublime truth announced in the Holy Scriptures and proven by all history, that those nations only are blessed whose God is the LORD. ----Abraham Lincoln
This is the famous Harley Air Cleaner Drip and has been obsessed over since the beginning of time, almost anyway. Many threads devoted to this subject under the terms like "misting" and "spitting". Look 'em up.
It is related to blowby but is not actually the same thing. Strictly speaking, blowby is ignited combustion gases squeezing past the piston rings which causes a build up of pressure in the crankcase which escapes through a number of places. One of those places is the breather tubes in the heads since the pressure build up gets up to that area too. Harley has decided to vent the pressure in the heads to your air cleaner by means of those little 1/4" black rubber hoses that go from the heads to your air cleaner backing plate. Along with the gases comes a bit of oil mist that, if it becomes a little excessive, builds up in your air filter and drips out the bottom of the air cleaner cover. Under normal conditions the mist is supposed to be sucked into the carb or FI body to be burnt up in the engine.
The causes and cures for this nagging little annoyance are, like I said, incredibly numerous. S&S, JIMS, Doherty, and many other guys have gizmos to address this problem which, by the way, gets worse as an engine gets older and the rings wear out or you pump up your engine with high compression and big displacement.
Now don't get a sweat going on this yet. Your bike is fairly new, I assume, and for you there might be a simple fix.
1) Check that your breather hoses going to the air cleaner haven't come off or split.
2) Make sure you haven't over filled your oil at all. A lot of guys actually run their engines about a half quart low on oil to avoid the Harley Drip. I'm not recommending this under filling, just mentioning it. Over filling is the cause of more cases of Harley Drip than you would imagine.
These two things are easy to check on your own without going to the dealer. If these efforts don't help your problem then it becomes the dealer's problem.
Excellent reply, milindh. Thanks! Now that I know that it's nothing that will ruin my weekend ride, I'm stoked!
__________________ ===================== Rob 2007 FXDB San Diego, CA
John 1:14
It is the duty of nations, as well as of men, to own their dependence upon the overruling power of God, to confess their sins and transgressions, in humble sorrow, yet with assured hope that genuine repentance will lead to mercy and pardon; and to recognize the sublime truth announced in the Holy Scriptures and proven by all history, that those nations only are blessed whose God is the LORD. ----Abraham Lincoln
Good explaination..and concisely written..except that although you seemed to be leading up to it,you did'nt get to the part where just (?) the downward movement of your pistons in their cylinders of even a brand-new engine with (theoreticly) perfect sealing rings compresses air in your engines cases that also has to be vented...same scenerio and remedies,etc. as you described..with "blow-by" adding to the issue as the engines wears.
Yeah,.and I just thought I'd toss that in,for the sake of anyone with a new bike/engine who might otherwise get the impression that if he/she is getting some of that "oily-mist" dripping..it must be from poorly sealing rings..which of course just "ain't necessarily so".. and,as you said,not to be overly concerned with.
__________________ "If at first you don't succeed, try again...then swear"
Mark Twain
I put a K&N filter and rejet on my sporty at the 1000 mile service and thats when I started noticing the blow-by. I was only getting it on the high speed runs on the interstate for 150 miles or so. Before our recent trip to Myrtle Beach I had the stage 1 air cleaner set up with screaming beagle filter installed and haven't seen a drop since. The blow-by is history and now I don't have to carry a little rag in my pocket to clean up with at every fill-up. Hope this helps!!
Uzi `s are neat. All my NFA class 3 stuff is gone. My buzz gun was a 1941 PPSH . Gave up my idea for converting a Win 94 to full auto. Some things in life are too hard.
A few months ago I put an old model breather tube on an 05 Sporty. Works but lots of fabrication to hold the backing plate on. No chain to oil so used an old model breather filter to keep oil off the tire. EPA never liked me anyhow.
Just wished John B. had done sickles and cars. Have this vision of having to squeeze the steering wheel to start the car. Still have lots of his stuff around the house.
Ah the blow by blow, blow by. Can't stop it so confuse it. I just take a small piece of cotton shop towel off a worn out one. Cut a piece that I can fold over about three times and make into a patch about 1-1 and half inch square and place between cover and filter. Out of sight and it catches all the drips. Usually last as long as the filter. When I clean the filter I replace the piece of rag. May not be high tech but it works for me. Just for giggles, I run a K&N filter, mostly a stock cover. and a kury vent system.
Blow-back... 
Linear Mode
