adjusting tappets on a Triumph Herald 1149 engine

[livo@saglac.qc.ca]

Adjusting tappets on a Triumph Herald 1149 engine 
Questions:
1. How do I know if I need to do it?

2. Is there a gasket between the engine and the cover over the
tappets?

3. If yes, what is it made of?

4. Can I put the gasket back, or do I need to have  a new one
before taking the cover off?


I look forward to comments and advice.
John Vincent