is there a place where one can go to find out the honda numbers that supercede old numbers? I am trying to find out if 13103-400-010 is equal to (old No.) 13102-400-000 or if these are interchangeable parts.
Those 2 part numbers would be interchangeable. The last 3 digits generally only mark small differences between interchangeable parts. Usually it is color or manufacturer or sometimes size. 000 is usually the first issue. Then if it goes onto a second model with a slight change such as black rather than chrome for instance, it will get the 010. Lots of times you will see 671 and 672, that may indicate a different manufacturer such as ND or Hitachi on electrical parts. The other time when the last three are important is if you are getting original Honda carburettor jets and the last three are the jet size so it does make a difference.
I hadn't really bothered to check what the part is. Since it is a .50 over piston, the 010 is probably the piston style from the next year or mid year change and might be different by a slightly different pin boss or skirt length or cutout shape or size. It is probably an improvement in wear or performance over the 000.