After 20 years of not riding my '66 A65L (yea I know this is the Triumph Board!) and getting it back on the road, I too was concerned with top end tappet noises.....to reduce the chatter I check/adjust clearances a couple times a year..and insert those funny looking orange foam things in my ears before donning the brain bucket...it sure is quieter now!
'66 A65L original '66 A65L "old school" chopper
Re: Noise from valves. How much is acceptable?#84539 10/28/057:28 am10/28/057:28 am
I use earplugs too! They actually remove all the non serious noises like tappets etc and leave you with the expensive ones like big ends, mains and gearbox noises. Also, I sometimes think my bike sounds like a bag of spanners but then pull up at a bike stop and people comment on what a quiet engine I have! If you let someone else give the bike a ride and have a listen from the roadside, you will find that it doesn't sound so bad after all!
I don't know if this has been mentioned but you can get solid washers to replace the spring things in the rocker boxes and these remove some of the clicking.