Engine breather system questions

[CanBike]

know it's likely been talked to death, but...

- there is a hose from the top of the block near the front, that goes to the heads. What does this line do?
- do the rocker covers really need to vent off condensation to the breather box?
- that leaves the vent at the back of the engine with the check ball (if upgraded) Does it really blow that much oil?

Thoughts?

[Antietam Classic Cycle]

I've read Guzziology, and searched the crap out of this subject... and I know it's likely been talked to death. But if someone might indulge me a few questions. (my bike is an 850T)

- there is a hose from the top of the block near the front, that goes to the heads. What does this line do?
- do the rocker covers really need to vent off condensation to the breather box? BMW airheads have similar design and they do not vent the rocker covers.
- that leaves the vent at the back of the engine with the check ball (if upgraded) Does it really blow that much oil? Was it originally plumbed into the stock airbox where the fumes were burned? Like on an airhead.
- has anyone ever plumbed the rear outlet into the back of their K&N filter and just burned it?
- is this all needed because of the the shallow oil sump whirling up oil from the crank?
- the fittings and hoses on the heads and rocker covers look ugly. Just saying.

Thoughts?

- The "Y" line from the top front of the block to the heads is the oil supply line to the rockers.
- Earlier models like the V700, Ambo and Eldo didn't have the rocker cover vent and didn't suffer from any condensation related issues. However, I still would not eliminate those vents as IMO they are important to help vent crankcase pressure during high speed running. Besides, what are they hurting? Oh, they're "ugly" and make removing the rocker covers (very slightly) more difficult. 
- Unless one has a clear hose between the engine and breather box, how would one know just how much oil is "blown" out of the engine at the big breather tube? It was originally plumbed into the breather box (there was no "airbox" to speak of on an 850-T - just a rubber boot with screen), where oil mist was separated and returned to the engine via the smaller return line.

[John Croucher]

Proper ICE crankcase ventilation is important.  A balance between a vacuum and pressurized crankcase is dependent on the operating range and characteristics of the engines use. 

Too much vacuum can pull intake flow past the rings.  Too much pressure can blow oil past the rings and out various crankcase openings and gaskets.  Where does this pressure come from?  Piston pump, past rings, past valve stems/guides.  Pull the valve cover off and you will see black staining around the exhaust valve spring.  This is exhaust gas that is blowing up the valve stem and into the crankcase.  Valve guide seals help stop this. 

Some high performance engines have crankcase vacuum pumps installed to reduce the piston pump compression that slow pistons down. 

If your set up is missing the stock air box and you are running pod filters. Buy the crankcase ventilation box.  Run the vented outlet to a fitting inserted into the backside of one of the filter pods to catch the blowby instead of venting to the air where it will blow all over your bike. 

I run a hose from the ventilation vent to the pod.  I cut the end at an angle and it is laying up against the filter element where the mist keeps the filter oiled and sucks blow by thru the intake.  It ain't no beauty contest under there, but the hose is much less messy than oil all over the tire, frame, clothes and bike.