How many miles can you usually expect to get out of a chain??? mines starting to develop a tigh spot so jus wondering how much longer i’ts gonna have left its done 12k mix of track and road and some of the teetgh in the rear sprocket are damaged too, anyone recommend a good chain and sprocket set?? wanna change the gearing too as never really use full throttle so would prefer quicker accelleration any ideas??
mix of road and track…and wheelies 
will give Ralph a call for you - he’s racing in the 675 series
either one down on the front if the sprocket size will allow, or up 2-3 teeth on the rear is equivalent. will give a bit more punch
if you change gearing too get a 520 pitch C&S set. down one on the front and up a couple on the rear will liven her up. if you aren’t sure if you C&S are deaded change them anyway…save you getting a hole in your leg and engine if it does go.