On my 91 k100rs , the PO disconnected both the tank overflow, and the CA emissions hose. I noticed that the hose (or at least, _a_ hose, which runs to the top of the engine, front edge, right under the fan) was just laying there, with the clamp still on it. No sign of a 1-way valve, unless that's mounted to the engine.
I wondered if this hose should be plugged with a vacuum plug/golf tee? Maybe it was, and the plug fell out.
