Better look closer at that manual, the spec is .08 mm. or .003". The range is .002"-.005" and I can tell you for a fact that the OEM setting of .003" can and will burn the crap out of valves. Use .005" as a MINIMUM and the engine won't see that at all, rather it will last MUCH longer in the long run as the valves on these tend to close up with wear rather than loosen up. Why? They are surface hardened only and once fuel went to true unleaded the seat wears faster than the tip. The bikes were built in an era of low lead fuel and that small amount of lead still performed wonders saving the valves. We are not there any longer.
Here's why they burn and why you have fits getting the same readings over and over. Simply put, look at the cam clearances in the head. They are .005" and even more. There is flat NO WAY you can hold a closer number than that with the loose cams being pushed around in the holes by the springs to alter the valve clearances to not be what you think they are. You can set as carefully as you want and say .002" and engine running will then not be closing that valve to get a compression leak and engine then runs like pure crap. Why you go .005", to make sure while running you got hopefully a truer .003" or so.
My first one of these I set close and perfect, just exactly as the OEM spec said. The bike promptly burned like 6 valves in less than 5000 miles. I'm no rookie setting valves either, been doing it for many years on all types of engines. The next head I loosened up to .005" after discussing the issues with others having same trouble and voila, engine then lasts forever.
The problem is so bad that there are those who look for the bikes at super discount as so many owners have set valves too close as well as the shops. Often you can redo the valves to looser and a motor that was missing before from valves not closing then goes to running like a bat out of hell. The carbs often get blamed for it and then carbs will be in a box to get bike even cheaper. You can make big money knowing that.
Honda knew there was a problem with setting them and attempted to change the marks in '82 I'm thinking, but the problem still there. Basically you can check the clearance and roll cam a bit and while still on the cam base circle the clearance will change one or two by simply moving it. Because the springs next to the one you're setting are pushing cams around in the head. It'll drive you crazy.