Similar question about the small o-ring, but for a 12/1991 built TDM.
The Haynes manual (circa 2000) calls for one, but the parts list that I have, 3VD_92.pdf, doesn't show one. A 1994 parts list don't show a small o-ring either. A 1996 service manual does call for the small o-ring.
The last full service was by a Yamaha dealer, and when I opened it up today, there was no o-ring present, it appears to be simply two machined surfaces with no o-ring or gasket and two bolts. The later models appear to a collar insert with the o-ring on the outside.
So, the question, do the old 850's use any kind of sealing, and if so, what's the correct part number? TIA
Mark
Edit: I believe I have answered my own question. Searched the PDF with the o-ring part number and found it as item 32 in the oil pump parts and item 31 is the collar. The exploded drawing has them in an odd position but there you go. It looks like the collar has gone missing at some point in the dim past, so I need to find one of those as well as the o-ring.
Edited by MarkH, 12 October 2018 - 09:57 pm.