Whether you are rebuilding the complete engine or just overhauling the Valve
gear drive train - the Exhaust
Valves and associated parts should be renewed preferably replacing all the interfacing parts at the same time - mixing worn parts with new can lead to premature wear of the new item.
You will probably wish to replace this related item:
Renewing all the parts of the Valve gear assembly at the same time is advisable. Enjoy our user friendly online purchasing system, with competitively priced parts and ultra low shipping costs - no company takes Japanese motorcycle parts more seriously than CMS.