it should show the speed in the lcd window as well as the feul tank level and mileometer(total mileage)if it doesnt then the speedo is eithe faulty which is very common or the multi plug on the back of it is not on properly or its got a bad connection there.ps if you end up buying a secondhand one the 125 and 180 speedoisexatly the same apart from having a red dial on the revs counter.i take it the rev counter works ?and you have the fuel guage working?the speedo just starts off with a 0 and goes up digitally as you go faster.
adam bike doctor
March 2010