Well, I believe with the metal mating surfaces clean and the gasket dry you will not be prone to leakage either. Triumph has come a thousand miles with the machining of the engine cases true, as to the old bikes. If you use a strong adhesive such as "Form a Gasket" you stand a good chance of damaging the soft aluminum when it's time to remove it in the future. You should endeavor to not put a scratch on the mating surfaces and it's a very soft alloy. Those guide bolts I mentioned earlier are really handy on the armature (Rt side) case cover, when arguing with the magnet inside and going back on straight and true.. You can use a silicon sealer, but, like I said, I have not needed any. So it's really your call.
