According to the official Honda Service Manual there is no adjustment. If the cam chain is worn/stretched, it needs to be replaced.
Here is a direct quote from the manual: "Measure the amount of the cam chain tensioner projects as shown (there is an illustration). Replace the cam chain with a new one if the projection exceeds 9.0mm (0.35 in)."
You need two chains and the part is obsolete. Here is some info from partzilla.com
214401-MF5-004 CHAIN, CAM
$157.80 $157.802PART OBSOLETE
I was gonna suggest that the tensioner on our motors takes care of "adjusting" the cam chains for the life of the chain...
But when all the tensioner uses up all its "adjustability" the chain needs replacement...
Thanks for the advise, I will check the tensioner to see if it has reached it's limit of auto adjustment. Going to also check again the valve gap is set right. Either way, I will keep riding until it's taken off the road in the summer (Harley time) and might look to change the chain if I can find one.
Finally got to check the cam tensioner adjustment - the projections on both tensioners is 6mm. The tensioner for the rear cylinder was stuck and the wedges could not be moved with out a little pressure. Both tensioners now move freely, this as reduced some of the engine noise slightly and the bike seems livelier. As both chains are within the 9mm service limit I assume I can leave them in.
Are there any other things I should check, I know the engine has some ticking noises as normal but this seems a little more than normal. Any ideas?