One of the first things I usually do on any bike I own is to vent the air cleaner to atmosphere. On my 18 Heritage I am trying to talk myself out of it. I have always hated the look of running a hose down beside the engine or having a filter hanging down below the air cleaner. I have put about 600 break in miles on the bike. Some of it rather spirited. Took the air filter out yesterday for a look. Wiped off everything and if there was more than 2 drops of oil I would be surprised. For the first time I might just leave it alone.

 

Just means the oil mist was going straight into the jugs. You won't see oil in the air cleaner unless the engine can't suck it in fast enough.

 

I've had many bikes with and without...the bikes without it have always run well with no obvious issues or longevity problems. The bikes with it, about the same until my '16 RK where it seemed to make a noticeable improvement. That said, I'm leaving my '18 alone for at least the first few thousand miles minimum. I've never protected my warranty before, but I am now, and the bike really runs great so far.

 

I just did this to my ‘18 fat bob. I do it to all my bikes. I like stock ventilator on the 114 so modified it.

 

I vented mine into the air cleaner but to the outside of the filter so the air will mix with the cool incoming air an the filter can clean the oil, if any.

 

I like it. Makes sense

 

Obviously, we're not talking about a bike with over 100k on the clock and some, as expected, worn ring blow-by. We're talking about bikes in good running condition. If you want to reduce or eliminate the oil ending up in your air cleaner, there's a simple thing to try first before ya start drilling holes & running hoses:

Don't overfill the crankcase.

I've gotten into arguments with people who should know better that the top line on the dipstick is NOT the: "You must keep it full to this line." line, when the correct meaning of that line is: "You must never fill it past this line." line.

There's a very good reason that the bottom line is the "Add QT" line. There's no need to "Add" more oil if the level is in the middle, or the 2/3 full, or 3/4 full line. The 3/4 full level does NOT mean: "Add 1/4 qt."

In fact, and this is important, if the oil level is at the 3/4 level, that does NOT mean that the bike is 3/4 full. It means it's 3/4 of the way between "Add QT" and "FULL". So it's only down a cup from the DO NOT OVERFILL line. Why try to keep in on the ragged edge of being overfilled? It's pointless.

I do my own services, and I certainly do clean the air filter every 5k, and it's certainly not snowy white, but it sure ain't drippin', either.

 

I shall be doing exactly the same to my 18 Fat Bob when it arrives. As soon as I get it back from the dealer. First mod of all.

It shocked me on my '14 Fat Bob how much oily carbon buildup was on the top of the pistons when I had the heads done at about 6K miles. I spent hours cleaning it off as that **** gets baked on good.



Before...



And after!

 

I seriously doubt that carbon build up can be prevented entirely with this modification.
Show me one with the mod that has no carbon build up.

 

I have always vented mine in the past and still had some carbon on pistons. So have to agree