But what about my second question?

 

No suction is required to pull crankcase air out of the breathers.

 

The answer is yes; the crank case vents itself, the fumes just need a path to escape.

I am not one that subscribes to the "run the oil level 1/2 quart low" approach. One should not have to deviate from the manufucturer's instructions, particularly recommended oil level. I am however a subscriber to the "vent to the atmosphere" approach; don't want the crankcase fumes going into the combustin chamber to accelerate carbon buildup on the top of the pistons.

I vent to the atmosphere via two hoses that connect to a "catch can" stuffed with the mesh material used in the head breathers for the same purpose, to collect the oil in the crankcase fumes. The fumes are then vented to the atmosphere via a hose from the catch can to a spot on the frame on the clutch side of the bike. At the end of that hose is a small in line fuel filter that is intended to collect any remaing liquid from the crank case fumes. Every attempt is made to vent fumes only to the atmosphere. There are variety of ways to do this; the below photos should give you a place to start.

 

You should not have that build-up in your cover every 2-400 miles. It is an indication that something is wrong.

There is no lubrication needed in the top end by directing into the air cleaner. This is an epa requirement to vent the crankcase air back into the combustion chamber.

No suction is needed, it blows out from crankcase pressure.

Below is a link on all the reasons why there could be extra "carry-over" or as it is commonly referred to as blow-by.

Also, there in this link are different things you can do to prevent oil build up in your A/C

https://www.hdforums.com/forum/oil-r...f-my-bike.html

As noted in the link, the most common cause is over-filling the oil tank. Most think that the top line on the dipstick is the full mark, but if you read the manual (or the quote from the manual in the link above) this is Not the case.

 

I keep mine right up to the full mark by helping the BB a little with a simple mod such as this:

 

Brilliant modification! what size drill bit and tap did you use as well as the hose barb if you don't mind sharing?

 

1/4" NPT; whatever bit size is charted for that tap; IIRC, that would be 7/16" but please confirm before drilling. This is required for the later SE backing plates. The breather hoses entered the early backing plates from the backside, so in that event, just run a 1/4" NPT through those holes and plug with a brass plug. The hoses will attach to the OEM breather fittings.

 

Awesome thank you, this is the only real easy way to vent to the atmosphere in a late model HD..... anything else on the market requires using outdated bracketing kits with related backing plates used in older Evo models costing way more $ than practical. Using a tapped hose fitting like this allows you to use any existing stage 1 backing plate commonly used on late model bike.

 

I used the DK backplate and put my own air filter on it. Just plane ol stamped steel with open breathers. Was less than $100.