I have a cbr954.. cracked a valve.. my machine shop told me all my exhaust guides are bad. turns out they are backordered from honda and can take 2 months to get. I bought some used heads and he is telling me that two of these exhaust guides are bad on this one also. I am now thinking he doesn't know the tolerance to check. since they are exhaust guides, shouldn't they be a little more loose from the factory then the intake guides(or valve stems) or are they the same? I imagine that they need room for expanding since the exhaust valves are not cooled by incoming fuel. I need my bike back and cant afford to wait or to keep buying heads until he find ones he likes. I would think there should be some wiggle in the guides/stems until the motor heats up to normal temp. Does titanium expand more or less then steel or alum? I have a race motor for a chevy and my forged pistons dont set to spec until the motor is warm. Opinions? Thanks in advance.