Hi, magpiemale, Its a serious job, easy to muck it up, any douts put your bike in to your Yamaha shop. My 1979 TT500F, bought new never went to the shop, 30 years- 3 motor+1 gearbox rebuilds and mods (port and polish etc) then sold as a collectors bike for NZ$4500 (payed NZ$2900 new) when I got...