Silicon Seals

I use commercially-made silicon gaskets on my Commando rocker covers. I also used some obtained from RGM some years ago on the gearbox inner and outer covers during a rebuild. None of them have ever leaked and, with care, can be re-used. The rocker gaskets are about 1mm thick.

i had a constant leak as i thought from my rocker inspection cover gasket. turned out to be the rocker spindles leaking beetween the cover and the spindle. the oil used to blow around the gasket and down the back of the push rod tubes giving the impression it was the inspection cover gasket leaking.

I have a sheet of 1mm Viton that I got from ebay and it's excellent for making seals like that. It was only a couple of quid or so.

The advantage of Viton is that it's resistant to fuel (not that you should have any there) and heat.

I also use silcone seals plus on the rocker covers and no leaks.

A sheet of cork makes any inspection cover gaskets I need. The paper original was useless but the cork has never leaked.

The paper original is indeed useless, I've had the same silicon gaskets on my rocker covers since about 2002 and they're still good ...