Speedometer change from 80 to 160 mph

I've wondered about this for sometime as the subject comes up periodically. I'm inclined to think - no experience personally - That the "Needle indicator spring" is the key. A slight increase in it's tension would give the higher speed range, sought after.

If that's what is in there, it could be the right direction. I have no idea how these things are made and function, but I would go along with you on the spring theory. So, it could be just this simple: swap the springs. Otherwise, experimenting and calibrating. I had the unit disassembled but not the guts - just to clean the 'glass' from the inside. I don't remember now if it can be taken apart easily but I'd imagine there is a non-destructive way. There has to be technical info somewhere on components used to build them, so there has to be a specific spring or maybe even they use the same one but hook it to a different spot there? That would make sense from manufacturer's point of view, simplifying production and making things cheaper.

On the side note, regarding the manufacturer's mind. I have four cylinder blocks, which are 99% identical by design, and I am shocked to see how different they are when it comes to the non essential details! Some have nice smooth surfaces, but there is one with quite a rough finish. Also, inside the water channels. Some very clean, some very rough with lots of irregularities.

My KZ1000 has an 80mph speedo, if I go faster than 80 then the needle swings about erratically until I slow down below 80 again.

Holly... Signed in from my phone. Good info, thanks. My laptop is in repairs finding out why it doesn't power up. Difficult to follow up on anything in the meantime.