Final Drive - fluid leak

Standard preface. Noob question.

2 questions regarding the final drive.

There are 3 large "caps" on the final drive unit. I'd like to confirm what they are (see image):
1. The hole to put the oil in (right side),
2. the hole to drain the oil out? (bottom).
3. What is the one on the top?

I have some fluid (final drive oil?) leaking from the top "cap." Is there a seal or something that would be causing this leak?

 

If I recall from another post recently, the top plug is a breather valve for when the oil is overfilled. If it leaks out of that, it means you filled with too much oil. It's like a safety valve for overfilled rear ends.

If I also recall correctly, there might be some sort of valve that needs to be replaced once it blows and starts leaking. I could be totally wrong here, though.

 

Duh, ya. If I did a search on "Final Drive" and "top" I found the answer as well. Either its too full, or I was driving it before it got warmed up enough (likely as it was quite cold the other day).

 

With bike on centerstand, pull bolt #1 and see if fluid comes out.
Wipe up excess, clean pumpkin, tell no one !

Then wipe your fork sliders, engine drain plug, shifter shaft, valve cover, and outside carb bowls. ( Shhhhh !)

 

The level of the oil should only be up to the number 1 plug (filler/inspection plug). With the bike on level ground on the center stand, the oil should just be visible when taking the plug off. If you can't see it or if you stick your finger down and it is a good bit below top it up. If the oil pours out, then there is too much. Let the excess drain out.

Even when properly filled you can get oil residue coming out from the breather at the top. Expecially in warm weather or after a long drive.

 

Really cold Hypoid will "Cling-together" and collect at the top of the Gears.

The fluid will start pushing out the Breather.
There's a long history of this problem with the Yamaha Final Drive.

 

Yep, I drove in -1 C today and there was quite a bit leaking - on the tire - baddd.

 

OK, looks like this problem is not the temperature or teh level. It's 8 C outside today, and I checked the level and it is right at the fill hole. And it's quite a bit that's leaking.

Any other ideas about what would cause this leak?

 

Anyone have suggestions as to what is causing this leak? I'm going to change the oil in the next few days to see if that helps - I just bought it so have no idea when it was last changed.