How do you open up the tacho guage?

[buzzawak]

Hi Guys,
I am installing a Wideband Air/Fuel Ratio gauge on the bike.
The plan is to in-bed the Air/Fuel Ratio gauge digital readout in the original Yamaha Tachometer.
It looks like the Yamaha gauges are a sealed unit, no way of opening it, to get to the bezel.

Question,
Am I correct about it being a sealed unit or am I missing some thing?

[pefrey]

I have heard that people have opened them but I wouldn't try it myself. So a search on replacing the faces of the quages. I know for sure people have done that.

[Fizzinatorr]

All i know about opening the tacho is that you have to put it in the oven

After learning that it never really interested me, so many better advanced tach options