Bottom chaincae bearing question on '03

[wienerwater]

Just changing bearings and maintenance, and when looking at the bottom chaincase bearing, on my '03 RX1 Mountain,(has reverse) it has 1 seal on it, on the inner/chaincae side. is this normal, and why would the outer side have no seal, just open, facing the inboard seal on the shaft? I am curious if this is normal, or maybe the previous owner had this changed and screwed up?Seems the bearing are all original, since sled had 400 miles on it when I bought it, and now has @900 miles.Since this seal stops any chaincase oil from lubricating it, like the other bearings, seems strange to not have a seal on the other side to at least hold the grease in.The bearing is in fair shape still.
I assume the newer models are the same setup, but can anyone give me feedback on this one bearing, as I am waiting to install this bearing and want to do it right is all.
Thanks!

 

[yamahamaniac]

I blew all of the bearings in that area of my rx-1 mountain with reverse at the end of the just past year. When I took the chaincase apart the bearings in there have no seals on the inside of the chaincase so the oil can get into the bearing. Kind of like a prepacked bearing except having the grease in the bearing it is greased by the chaincase oil. So I guess the previous owner put the bearing in backwards.

 

[wienerwater]

Bottom bearing has seal on inward side only, to keep chain debris out, yet enough oil seeps through the seal to keep the bearing happy. You can grease the bottom bearing before assembly, with seal side facing in.

 

[yamahamaniac]

I don't think that's the way it's supposed to be. If the oil is seeping out through the seal enough to satisfy the bearing then you are losing a fair amount of chaincase oil aren't you? The oil level in mine never changed all of last winter. The only time it went low is when I took the chaincase apart.

 

[wienerwater]

Well, as weird as it seems, that is the way it works. I never thought about it much, until I talked with my friendly Yamaha mechanic, who is not bs'er, nor an idiot, explained it to me. The amount of oil is miniscule, not a huge noticeable loss, but is enough to keep it with a film of oil.
If you look at any photo's posted of a chaincase, you can see the seal on the inside, or call a dealer and get it explained.

 

[yamahamaniac]

Haha well I guess mine was in wrong. Should be right now though as I had to send her to the shop to get the gears fixed.