After finally getting into the gearbox and fixing 5th gear, rebuilt engine and test drove bike. Gears are perfect, but I noticed a constant whirring noise that was not there before. It's from the bottom end somewhere........... Pulled off the head and cylinder again, plenty of oil everywhere it should be, cylinder and piston are still like new. What I did notice was that the water pump weep hole had water pouring out of it.....it never did this before the rebuild. Wondering if I have damaged it somehow and if so would it make such a noise? Any other ideas.......?