Replacing spedometer

[justify]Car crossed the double yellow line, so I dove for the curb, wound up sitting on the asphalt. I was fine but my speedometer was dented, broke its glass, no longer lights up, and is a little weird with the trip odometer. Got a new instrument cluster and I'm getting ready to hang it on the bike, but ...

I've got a question about the main odometer. I know there's some sensitivity (as in a legal issue) about messing with the mileage reading/reporting on a motor vehicle. So, how can I get the replacement odometer to match the old one?

This is on a KZ750H1, or in english, an '81 750 LTD, although I'm pretty sure that makes no difference; just being thorough.[/justify]

Are you sure about a legal requirement on a vintage motorcycle?  

There is no simple or easy way to do it as the meters aren't intended to be opened.

As far as I'm aware there's no need to worry about the odometer being re-set to zero.  I've had gauges rebuilt by ZResto and he will leave them where he finds them or re-set them as the customer wishes.

If you are only a couple thousand miles off, remove the speedometer cable from the front wheel and connect it to a high speed drill. I did this a couple times, but had to let the drill run a full day to get 2,000 miles. 

I just put a brand new speedo on my sons Z650, it now has nearly 2000K's on it, I don't think anyone will care too much, if you are worried about it for resale, just keep the broken speedo as proof of miles done before accident and add new miles of new speedo and its all good. I wouldn't worry about it at all....