I'm trying to clean the valves on an old TL250 but am not getting much progress.  I have been using oven cleaner and the intakes are getting pretty clean but not the exhausts.  Is there a better way?

Paint Thinners works good for removing carbon.

put eclectic drill in a vice sick valve in chuck use henry cloth or sharp screwdriver like you wood or metal  machine wood shinny like new allways done it  cars tractors 

wire wheel on a bench grinder works fine.

Can 1976 Honda valves be resurfaced?  It sounds like some valves can not.

A kitchen knife would work OK, if you can sneak one out of the kitchen.  To resurface the valve you grind a new surface into it at the correct angle, usually 45 deg.   There are many Heath Robinson ways of doing it, if you don't have the correct machine.   Don't forget to lap the new surface into the valve seat with grinding paste, for an air-tight seal.