I am having problems with my bike..2007 Polaris sportsman.  For one It shows 0 RPM when it is running. All others are fine,(Time,speed,miles ect.)The second is it wont keep a charge on the battery.  If you can help me out that would be great..
Thank you,
Karen  

sounds like you have a short in the tachometer which in turn could be causing the battery to discharge prematurely, check all of the wires to the tachometer see if any are loose or broken, also check to see if you can wiggle them around and the tachometer begin working.  

Thanks for the reply, Can you tell me where the tach wire is at and how will i know witch one it is.?
Thank you.  

go to the back of the tachometer and trace the wires coming out of it.