speedometer problems

Ok I am finishing a 1980 kz 1000ltd project so far ive replaced almost every thing it came with no speedo drive for the front wheel and I think thats were I went wrong I got one from a police bike and a new 2240-60 speedo running it today ran it to 80 and felt way to fast let my brother on it he said the same thang is it the drive unit a different ratio or something else

I don't know about the ratios, but a really quick and dirty test would be to get a buddy/relative with a bike or car that has a known good speedo. Have them pace you at several different speeds and record what you see on the bike versus what they see on theirs.

Do both bikes have a 19" front wheel? I think so. Do both bikes have a speedo that only goes to 85 mph? There was a range of Kawasakis that did. Maybe you have an 85 mph calibrated drive?

There are a lot of free GPS speedo apps for a smart phone. I have used them to make sure mine was on. I calibrated it against my car speedo first and it was dead on it just lagged a few seconds. That may have just been the GPS chip in my phone though.

I have a speedo drive from my 77 KZ1000a1 if it will work for you. Not sure if they are the same.

I checked with gps 110 at80 so I swaped to a spare within 3 mph now so im good