Sq 4 Primary Chaincase

[Brian.Challinor]

Are gaskets required for the primary chaincases or is sealant suffice?

[brenton.roy]

Hi Brian, although sealant would probably do it by itself, I use a gasket and the grey yamaha etc. bond. The joint surfaces aren't that spectacular.
Brenton

[pete.collings]

If using silicone sealant. clean both surfaces of all old gasket etc and wipe over with solvent to remove any residual oil, then put a thin layer of sealant on this surface and allow to cure for as long as possible (overnight if possible). If there are any nicks or irregularities in either surface, put a little more sealant in this area.
Once cured, smear the surface with oil, and carefully replace the cover, trying to avoid scraping the silicone layer against anyting in the process.
This should allow you to subsequently remove the chaincases without damaging the silicone layer, in case you forgot to do something whilst the chaincase was off.....
If using silicone sealant on joints where there is engine oil circulating, I use a minimum of silicone and spread it only on the outer edge of the surface, to lessen the chance of it squeezing inwards when the joint is tightened. I also do not oil the surface, but allow the silicone to partly cure before making the joint, again to lessen the distance it might squeeze out into.
Lumps of silicone can have a disasterous effect on oil circulation if they break loose inside the engine!!