787 Counter Balance Bearings

[IDoSeaDoo]

Hey guys, I'm looking to rebuild my 787 CB, specifically the bearings. I'm wondering why one is open. It seems that the open bearing is the one that typically fails. Here, my open bearing is more worn than the sealed. I'm considering using a sealed bearing on both ends. I believe the two bearings are identical in size. I think the open bearing is meant to be lubricated by direct oil or grease and not intended to be used in a 2-stroke application. This is a poor design. Since the CB gear touches the crank gear, it'll get its lubrication from it, as that will be exposed to the fuel/oil flow. However, that open bearing would get next to no lubrication as there is no such flow past it. Using a sealed bearing there would also not cause any sealed voids, so I really don't see the point of using the open bearing there. Anyone know why they use open bearing there? I saw a post on another forum suggesting to do this, wonder if anyone has any insight or experience.

The bearing number I'm coming up with is 6304-2RS, a sealed bearing 52mm OD x 25mm ID x 15mm W

I will definitely avoid using the chinese brands.

 

[mikidymac]

It gets the same 2-stroke oil as your crank bearings which is plenty.

No need to reinvent the wheel here, the open bearing will get more lubrication than the sealed.

As far as failure plenty of the sealed ones have blown out also. The open ones typically go because of water sitting in the cases which also ruins the crank bearings.

 

[IDoSeaDoo]

I"m gonna go ahead and give it a shot anyway, getting a great deal on these SKF bearings. I know the original story plays out, and since the sealed bearing seems to work well on the other end, it should work just as well here. THe benefit is that I will not get water into this bearing from moisture. I'll try and remember to update this once I put some hours on it.