dunno if its normal or what --have an 88 xr 600 with big bore kit and cam. makes great power! But on decel after getting on it if i pull the clutch in i get about 3 distinct taps from the engine. Does not do it if i let the engine slow down gradually with the cluch out or down shifting. I adjusted the valves friday and i know they are getting oil and are set right now --but still does it. I am not too concerned as it runs great, just curious as to what it is. Talked to the prev owner who tore the engine down looking for it and everything was honkey dorey.