The tappets noise did reduce when we put the new oil in but then it got louder, possibly indicating that the oil isn't circulating properly. The buzzing isn't always there, just when i put my foot down a fair bit usually. How am i ever going to keep revs below 3000 for 300 miles when i'm finally allowed to drive this thing on my 21st birthday?
and yes you're right, the bottom end of the engine hasn't been touched.