found inside cb77 crankcase

[prodigal son]

The Super Hawk I bought in June, having sat since 1991, I decided to do some disassembly. Removing the oil pump on my CB77 project I found this particle of metal debris by the oil screen. Knowing very little about the innards of a CB77 crankcase I am asking the experienced of this forum to maybe identify what I it might be piece of. The top looks like it was apart before, which might be a clue as to why it was apart. The penny is for scale. Thanks, Gary

[mike horvath]

Interesting piece. Is it a ferrous metal? Does it appear to be one piece of a few? Like the arch faces are clean breaks or rough like it eventually cracked and tore on one edge?
Being small in diameter (looks maybe 12mm) I’m thinking cam chain tensioner bits but that would be the roller center if it metal. You can check that though. I can’t find much else from the top end that looks like that in color and metal. Looks fat to be a spacer washer in the bottom end. Tough to say. But, since you’ve decided to investigate, maybe time to remove the motor, flip it over and remove the bottom case half for inspection if that can be done by you. Things like this drive me nutty.

[prodigal son]

Mike, thanks for the response. Here's another, more close up picture. The bore is the size of a 6mm bolt and a file barely cuts it, so it's hard and brittle. I removed the clutch assembly. Looking at the Honda parts manual, the chain tensioner bolt 6X30mm is supposed to have a washer under the hex called (washer, locking). (90432-259-000) There was none. I can't seem to find a good picture of one. Also, below the tensioner is a cast hole in the lower case that this piece could have fell through and landed where I found it in a bit of sludge by the oil pump screen. There are no other possibilities in the clutch case where I see it could come from. I'm thinking, maybe the bolt came loose, the washer cracked, a piece of it was found and removed, and the bolt replaced with what I see is locktite, and closed up. I looked in all the holes with my borescope until my eyes crossed and found nothing else. So I'm going to move on to the rest of the restoration. Thanks, Gary

[Tim Allman]

I'm puzzled by this too. However, I don't think it has anything to do with the cam chain tensioner. I disassembled one and didn't see anything like that. The tensioner is easily removed without removing anything else. If that was part of it then it should be obvious both in appearance and smoothness of operation.