Ok so I noticed yesterday on my XV125 the speedo states Km/h on it and has the usual speeds up to 100, obviously at first you would assume the numbers are in Km/h but they don't as I've checked with phone trackers and such, anyone know why is this. Doesn't say MPH at all on speedo 

Someone may have fitted a converter on the back of the spedo. Or a different ratio drive to the front wheel. Then the km's will be mph. 

Normally cheaper than a replacement spedo even if it does squew the mileage figure for the bike a little. 

 

Does that mean the actual mileage is in kilometres until such time the converter was fitted, and presumably be a lot less than if it was on miles from the start

Yep. Although recoding in miles will be less than km.

There should have been some sort of record of the change. 

It was prob noted in an owners manual or fag packet some time. What the mileage was at the change.

Dont forget removing the device gives you a lower milage bike if it bothers you.