tach sensor?
 

I was just out messing around with my koso gauges. I knew something was up when in third gear at what the tach said was 6k rpm the Speedo said 96km/h before I changed gauges it would have said 120km/h. So I tee measured the tire circumference and got the Speedo part organized. When I went to set the tach again I followed the manufacturers instructions for 4 cycle 2 piston and it said the bike was idling at 3k rpm. I set it to 4 cycle 4 piston and it said I was idling at 12-1300 rpm. My question is this, is the tach sensor wire (y/g I think) corrected for the gauges to read?