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Just for the record, it is PCV. The bike does not have EGR.
Technically, the "Airhead" started with the 1970 models. It had the older round spring-loaded board covering the hole and moved up and down with changes in crankcase pressures. The /2s just before the /5 had a different mechanism. On the front of the engine is a rotating plate with holes in it. It was designed so that when the plate/holes reached the correct point, another hole in the case lined up, letting the pressure escape through the aligned holes. The pressure didn't vent directly to the atmosphere but ran through a series of channels until it came out of a small breather tube on the lower left front side of the engine block.
From my own experience on both a '92GS & '76R90/6 I was surprised at first hat there was oil present in the tube.
In both cases the valve was working as designed. As stated before there will be some blow by even in normal operation.
Two things that I have learned with my bikes that cause oil consumption to vary.
Kurts reply X1.
1. I noticed when the oil was kept "topped off" oil was consumed until the oil was at about halfway between the high and low marks on the dip stick.
2. While riding my first Airhead, I kept the rpm at 4000 or 4500. The local mechanic said he decarbonized the heads and pistons while doing a top end reseal at 30,000 miles. The question I asked was what could be causing the carbon buildup expecting that it was crappy gas or incorrect jetting.
He asked what rpm I ran at.
Then he said to run at 5000 rpm.
I've noticed a small increase in oil consumption at 5000+ rpm but both bikes run in a sweet spot at 5000 rpm.
Bill