I bought a cheap motorcycle for temporary transport and to convert to an electric bike later in the year. The tachometer was missing the needle so it was impossible to see what revs you were doing. Whilst working on the instrument binnacle to convert the lights to LED (instructable posted here today) I decided to have a go at fixing it. It turned out to be really simple. I used a length of wire insulation as the post, pushed that on to the shaft and then glued the end of a small cable tie on to the post to act as the needle. Very simple and extremely cheap at 0.00c. Works like a treat.