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Hi. When I bought this bike it had these two green rubber plugs. What is the purpose of these plugs? They completely stop the airflow for breathers. They look like an aftermarket upgrade but it doesn't seem healthy for the engine.
Unless someone blocked them off that heavy breather has internal holes that route the gunk into the intake...but the crank case pressure would have to come out of somewhere so it's safe to assume it's functioning as designed.
Evo case needs to breath on the strokes, or it will cause the case to go either under a vacum on the upstroke, or pressure on the downstroke.
As for this, maybe still passage from the breather into the intake, so breather channels are not blocked.
But seeing a copper line, so wondering it that is the line it turning a bottom breather, into a top breather with that air intake system.
The bottom breather has the port at the location as the air filter in the below photo, and since end of copper line is king of dirty oily, go to wonder if that is what is going on.
On this,
Still breather bolts with foam, and the chrome cover still allows the heads to breath behind the caps (leaving a oily mess around the engine there instead).
In some case, vent plugs may just have chrome covers over them, but still allow the breather bolts to still breath, or bolts have passaged from the bolt to dump into the intake manifold isntead.
Myself on a 97 with is a top breather and the older Screaming Eagle K&N filter system, I installed a catch can for the case to breath into the can to catch oil, not puck into the intake or side of the motor instead.
Bottom line, bottom breather, or top breather when the vents are in the heads, case has to breath during the strokes. As for where the oil from the breather goes, not the best to dump that back into the intake manifold for the motor to burn the oil to keep EPA happy, and instead, either catch can, or to the ground instead.
This way, the bike can still mark it spot, like the older bikes up the shovel head, that oiled the primary chain with a drip, but allowed that oil to just leak out of the primary cover via it bottom drip port instead.
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Plugs for Breathers
