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Yes you have to bore the seats to the valves and there is a specific tolerance.
Valve seat for the intake should be .015~.020in less than the actual valve O.D, this would be a variance of .2~.5mm.
Valve seat for the exhaust should be .005~.010in less than the actual valve O.D, this would be a variance of .05~.25mm.
Also undercut is important on intake valve opening before the throat cut the undercut should be about 60* in pitch, while the exhaust valve undercut can vary on the exhaust throat between 55~70* in pitch.
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