Hi SOHC Fans,
None of the shop manuals I have (Honda, Clymer, Haynes, Hondaman) list different valve guide bore (ID) values for the F2/F3 era bikes. I know from my readings that these bikes were notorious for wear here, due to the altered angle on the cam. Stem-to-guide clearances of 0.05 (intake) and 0.08 (exhaust) seem to be the recommended maximums.
Well, this bike certainly is worse than that on the exhaust side... Does anyone have measurements I could compare mine against? Are the exhaust guides just that bad?
My '78 CB750F3:
Typical intake valve stem OD: 6.59-6.60mm
Typical intake valve guide bore ID: 6.63mm
Stem-to-guide clearance: ~0.03mm (OK)
Typical exhaust valve stem OD: 6.56-6.57mm
Typical exhaust valve guide bore ID: 6.95-7.10mm
Stem-to-guide clearance: ~0.55mm
Guess I'm getting new (brass) guides from Dynoman...