As far as I can see, that 67 Euro reed valve housing that replaces the OEM breather, has one advantage, at least in principle.
It adds close to zero volume to the crankcase volume, where any other breather check valve would add the volume of the connecting hose, plus the volume of the OEM breather itself. Which in turn should help lower crankcase pressure a fraction.
On my 2 aircooled/ 2valve Ducatis, the OEM breathers are in fact a reed valve. However, they are crankcase mounted, as the only passageways between heads and crankcase are the oil drain bores. Anyway, those breathers work flawlessly, and the Ducati engines are 99.9 % oil tight, despite having vertically split cases, just like old British twins.
It adds close to zero volume to the crankcase volume, where any other breather check valve would add the volume of the connecting hose, plus the volume of the OEM breather itself. Which in turn should help lower crankcase pressure a fraction.
On my 2 aircooled/ 2valve Ducatis, the OEM breathers are in fact a reed valve. However, they are crankcase mounted, as the only passageways between heads and crankcase are the oil drain bores. Anyway, those breathers work flawlessly, and the Ducati engines are 99.9 % oil tight, despite having vertically split cases, just like old British twins.