What is the extra sump plug for?

[Kane 329]

Looking at the back of my oil sump pan, there is a large plug screw to the right of the drain plug. The parts catalog shows only the drain plug and the oil line, but not this extra plug. What is this plug for?

 

 

[docc 3,762]

It is a vestigial structure left over from earlier wide sump models that had two oil return lines from the spine frame (one on each side of the spine).

[Kane 329]

Damn you’re good. Thanks, docc!

What are those oil lines for, exactly? 

https://en.wikipedia.org/wiki/Vestigiality

[docc 3,762]

To return the liquid portion of the crankcase ventilation back to the sump. Instead of into an old Castrol® fork oil can or Coors® can.

The V11 crankcase ventilates from a fitting (#14, first diagram) on the rear, upper right of the block inside the clutch housing, through the nefarious, shaped flexible hose (#18 in the first diagram) under the spine frame that connects to the bottom of the spine just behind the headstock.

From there, the vapor portion is extracted (more or less) from the banjo fitting on top of the spine at the headstock into the airbox (#16/17 in the second diagram) while the liquid portion drizzles down inside the spine to the return line which dribbles back into the sump.

[Kane 329]

Awesome. Thank you for your detailed explanation and images. I did not understand this scavenging system. I hope the interior of my spine is free of rust, insect carcasses, and the like! I suppose the oil drizzling through there helps keep it clean. Triumph used the large down tube frame member as an oil tank on bikes in the 1970’s, so I guess the appropriation of frames as oil vessels is not uncommon.

[wdietz186 11]

Noticed in the case breather pic that the cam bearing plug? is filled with a sealer, is that a leakage issue area? or it just being cautious? When reassembling my engine I looked at it and decided that being a fairly substantial aluminum plug it shouldn't be likely to leak. Hope I'm not wrong as it is back together and running!

[docc 3,762]

24 minutes ago, wdietz186 said:

Noticed in the case breather pic that the cam bearing plug? is filled with a sealer, is that a leakage issue area? or it just being cautious? When reassembling my engine I looked at it and decided that being a fairly substantial aluminum plug it shouldn't be likely to leak. Hope I'm not wrong as it is back together and running!

Yessir, the cam bung can leak. One of eight places in that space that can leak . . .