First Post KZ200 '77 Speedo Replacement

Hi first time on here and have had a good look for this before posting so hopefully I don't embarrass myself...  I have a KZ200 1977 and the speedos are a touch trashed.  In fact the whole bike is rusted through so it's getting the full works.  My question is that I am looking to replace a mechanical speedo gauge with another mechanical gauge and I understand the need to match ratios etc, and I could work out the k value using tyre circumference and distances travelled etc which is all very interesting learning and probably will do at some point for accuracy, however I have read several times that the K Value of the speedo should be in the bikes literature or written on the back of the speedo itself....

I have tha haynes, original workshop and owners manuals for the bike and it doesn't state it anywhere, again unless I am being stupid which is a distinct possibility.  Also my gauges are unreadable on the back.  There is some evidence of print there but nothing I can read.  Does anyone have this figure or a speedo that states it?

Many thanks

Welcome from Leicestershire

most Japanese speedometers are 2240 revs per mile. some of them are stamped on the back. mine says 2240 revs = 1 mile. using the 1978 kz200a diagrams. with a 17" wheel and 2.65 gearbox ratio. yours is probably a 2240 speedometer. ps: you might want to verify the year. a motorcycle mfg'd in 1977 could be a 78 model.