So I ran my 2008 YZ450F without water for a day or two ( I know ). I took the motor apart and the exhaust cam shows some significant heat discoloration where it rides against the aluminum of the head. The camshaft has a bluish color to it centered around the cam journal but the discoloration does extend into both cam lobes. My question is do I need to replace the exhaust cam? A friend of mine suggested that whatever heat tempering process was done at the factory has been ruined and the cam will soon fail. Basically, he says that the heat has weakened the metal. Is he right?