Oil change/return question

Have just changed the engine oil in my '73 750 (Hi-Rider to roadster swap) that I've made numerous posts about. Drained the tank, the sump and changed filter (spin on cartridge type from Andover Norton) and refilled. Have started the engine breifly to check for leaks, but with the tank cap off, should I be seeing oil returning to the tank at the sump return line which I assume is the tube with exposed end just under the cap? If so, how long should it take untill it starts returning oil? This has me concerned as I ran it for a minute or so without seeing any return oil.

The horizontal tube exiting into the oil tank filler neck is the
breather . The sump return is the vertical one on the back side of the neck - it’s opening is somewhat pinched off .

I am not sure how yours is set up but I think the exposed tube you see is the vent tube from the engine for blowby gas.
On my bike, it comes in on the gas tank side of the oil tank and is exposed.

On my 73 850, the oil return comes in to the oil tank on the rear wheel side of the oil tank and has a baffle over the opening to direct the oil down.

On my bike, the vent tube has a one way valve on it and it spits oil into the oil tank as the engine is running as I guess the oil is splashing around in the engine and some gets into the vent tube and (via one way valve action) gets pumped to the oil tank

Dennis

If you have fully drained engine sump,cleaned the sump mesh trap etc, then it will take 3 or 4 minutes of idling before enough oil has filled up the sump volume before getting drawn back thru pick, then to oil filter and finally out of the tank return port.
This is what my 850 does when doing that same proceedure.

Thanks Richard Tool, DennisMo, and L.A.B. Had me worried there for a while. The returen line as you've described is returning oil, and the line I was referring to, as you've said is a vent/breather line. Thanks.

quawk said:

Thanks Richard Tool, DennisMo, and L.A.B. Had me worried there for a while. The returen line as you've described is returning oil, and the line I was referring to, as you've said is a vent/breather line. Thanks.

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There is also the fact that the returns are not in the same location, 750 to 850. It is lower in the neck on the 750 so might be harder spot initially.

As far as I can remember (I'm old, so memory is probably slipping but...) this is the first dry sump oiling system bike I've ever had. So although I understand their basic operation, wasn't sure about which was the sump return. That's my excuse anyway.