last night the light went out for the tach on my sons 01 r6 all the other gauge lights are on. is the tach light a regular bulb or an led and does the gauge just open up to replace the bulb?

You can take the cluster apart and then the bulb sits inside a little twist-lok connector. It's a real small bulb like a 134 but smaller, I had a hard time finding them. If I remember right I ended up ordering them through bike bandit because all I could source locally were 1 size too big and forced into the connector.

It is listed as Yamaha Part Number: 4YR-83534-00-00 Bulb (12V-2W T5)