Thank you Ace. I may be very wrong but would not it be rather .01"? I am thinking that at .001" the valve clatter wold not be very audible especially that the valve stems also expand due to heat.
The way I read the question is, "how much does the cylinder barrel expand from cold to operating temperature?"
I take this to be asking how much does the bore expand.
Although some cylinders have aluminum fins, the bore is usually made from some type of cast iron and this is what controls the growth of the cylinder.
The coefficient of thermal expansion for a typical cast iron is about 6 millionths of an inch per degree F, per inch of size.
Figuring the typical cylinder will be about 250 degrees F at operating temperature that is about 175 degrees F above room temperature so we have, 175 X .000006 = .0011 (per inch).
The bore on a RE 500 is 84mm or 3.307 inches in diameter so, 3.307 X .0011 = .0035 inches of expansion at operating temperature.