Scene: OldSchool '70's Jap motorcycle dealership, out back in the shop.
Sealers were only used between machined, ungasketed aluminum surfaces.
All gaskets and seals were assembled dry, per mfg directions. Sealant usage was considered unprofessional and frowned upon, unless used to solve difficult or damaged surfaces. Of course, these kinds of bikes were still relatively new, and shop procedures included thorough engine parts cleaning. Using gasket sealers would guarantee difficulty in future servicing, possible damage in disassembly. Plus, it just added cost and labor when it wasn't necessary.
Fast forward to today. After 40+ years of checkered history, who knows what the condition is of these old parts. Seems that there's a significant incidence of warped head/cylinder mating surfaces, and 5Twins has posted much about headgasket sealing methods. Understandable, that's a heavily stressed zone.
But, the bore surfaces where seals fit don't see that kind of stress, and would normally be expected to handle dry seal install just fine. *Unless* Now we're back to the 'checkered past' thing. If someone tried to dig out a seal with picks, chisels, roofing nails, claw hammers, prybars, detonator caps, ...etc., THEN you've got a problem. This calls for careful inspection, and prudent solutions on an as-needed basis. Grand Mal slopping of sealer on everything isn't advised...
