to vent or not to vent?

[Elkonastick 10]

So I'm going to replace my coolant overflow bottle tomorrow, it's on a Soob EA81. What's on it now is some kind of water sippy bottle, like they give you in the hospital. See pic. The bottle I'm going to use has several access points for the tube. Bottom, side, top. My thinking is run tube from system in the bottom, that way suction point will always be submerged vs running in from top with pickup tube ran to bottom of bottle. Then top point run vent tube out through bottom of cowl. The current sippy bottle on it now is not vented, by design? Am I missing something? I've seen it done both ways, vented and not vented. The bottle I plan on using is a generic automotive bottle and has option of being vented or not. I seen a pic online somewhere of the same bottle I'll be using installed on a plane with a soob engine but didn't pay attention to how it was plumbed and of course now I cant find it. I got a feeling I'm WAY over thinking this. But better to ask stupid questions than risk seizing up a motor. Thanks guys, I come here everyday and learn something every time.

[nlappos 413]

From what I know of overflow bottles, they must be vented to the atmosphere. Your idea to connect the line from the radiator to the bottom seems like the right idea, as well.That way only fluid is exchanged with the radiator.

[SuberAvid 617]

Yes, run the overflow tube from your radiator into the bottom of the bottle and just put a very small vent hole in the cap, about a 1/16" hole is all you need to vent the cap.

[Elkonastick 10]

Thank you gentlemen! Current bottle is pretty hokie and unvented. I have a coolant system bottle for big street bikes coming.

Edited 30 Jan 2019 by Elkonastick