Where did this hose come from???

[beta_kevin]

First time poster. Still getting comfortable with my newly purchased 1980 XS650 Special II and took it out for it's first decent run...about 80 miles. Bike ran fairly well...it died a few times, but nothing crazy.

My reason for this thread is...after running and parking it for about 24 hours, this hose popped out and looks to have leaked some gas I believe from the smell...though it looks kind of oily as well. I can't seem to figure out where the hose was connected.

Can anyone identify what this hose is or where it was originally connected?

I figure with a bit more digging I'll figure it out...but I thought this might be a good excuse to break my silence on this form.

Here are some pics:

 

[weekendrider]

A drain hose for a modified crankcase breather?
Between the cylinders on the rear/back/carb side of the motor is a box with a hose (1/2 -9/16 size) coming out and following the back bone.
OEM it would bend down the backbone and run to a "T" which had hoses to each airbox.
Some cut the hose and install a brake booster check valve. The drain tube is a smaller size like your picture.

Welcome to the site.

 

[beta_kevin]

Thanks for the response weekendrider, that makes sense as to why it's a mix of fluids.

 

[MOSFET]

Could it be an old battery exhaust vent tube? On my XS it was in similar diameter, as the hose on your picture.