Hardened Valves

[Williegunn]

I have done a search but cannot really find the answer I'm looking for.
If you were rebuilding a Comet engine would you fit hardened valves and seats?
Or can you just run it on petrol + additives?

M

 

[timetraveller]

I ran my twin on petrol + Millers and after a few years the valve seats were about half way through and I had to slacken the tappets every few weeks. You will find that some people will tell that they have not had this problem but on talking to a very senior Ph D in automotive engineering it turns out that there are certain combinations of revs. compression ratios etc. which will lead to much more rapid wear than others. My bike had 9:1s and once out on the road would typically be running at about 3,000 - 3,500 rpm. I would fit hard seats but others will advise you differently.