valve lash caps

Sorry, no answer for your question, but I started reassembling my Mk3 RH4 head, intending to use mushroom adjusters from AN.  However, just as you have found, though without lash caps,  whilst the inlet adjusters nicely centred on the valve stem tips, the exhaust adjusters contact themselves tips right at the edge of the tip nearest the rocker.  This seems strange, and makes me wonder whether it will result in premature snd uneven valve stem and guide wear.

I asked about this off-centre exhaust adjuster contact here a while ago, but there was no real explanation or solution, so I am still puzzled and the head remains unfinished.

Its not unknown for the valve operating geometry to be a bit out. It may be beneficial to adjust the action by changing the lengths of the pushrods and valve stems . This was done to the 750 motors at one time by the factory who lengthened valves and shortened pushrods. If valve seats have been worn and valves sunk in this can be just one reason. Action that is too far out can break the adjusters cause rapid guide wear and waste power. 

Robert: If you are comfortable with an alteration here is how I got the valve tips/rocker arms lined up. The rocker arm can be moved side to side by removing the spring and using solid shims on both sides of the arm to achieve centering. I got the solid shims close to final thickness and used the stock Norton shims for final fitting. Fore to aft centering required Commando length pushrods, Atlas length valves, and lash caps with shims. My bike has run this setup since 1980, has run the Alcan Highway, vintage raced from 1996 to 2004, and has 31,000 road miles since. Mark

Thats really helpfull Mark and gives the orriginal poster some idea of the likely mods to achieve the ideal. Its clear that to properly diagnose any issue some time needs to be invested in observing the action ( with a very light test spring ?) ,and some experimentation with a range of spare parts to alter the centering of the motion . Sounds the ideal project during a winter layoff  to get the gray matter going. There has been an article in Roadholder on the issue.  Valves angles are sometimes changed on heads that are Tuned and i can imagine that  this will then need  some complicated correction of the action.