Aftermarket Speedometer

[Dolby67]

I see that there are many UNIVERSAL speedometers out there. But how do i know if it will work with my bike.


When I drive 50 mph - will it say 50 mph or 60 or worse yet...40.

Is there a way to adjust those mechanical speedometers?

Or....is the CABLE the one that spins the needle and if the cable is OEM then I can place any speedo on the bike and it will be accurate.

[AndreLindholm]

I have a stock speedometer from a Cb450 on my Ft500 so if you find one that works for that bike it should work. I think it is the speedometer gear thingy at the front wheel that decides what ratio you need on the speedometer. And when you order a speedo you need to make sure that you have the right Ratio or else the speedometer will show a non accurate speed. Try to find out what ratio the ft500/cb450 has and go from there.
Does anyone know if Honda used the speedometer ratio on all bike during this time?

[scottly]

I believe Honda used the same ratio speedometers on most, if not all their bikes; it's something like 60MPH=2200RPM at the cable? I was looking to swap a '77 CB 750 speedo onto my FT at the time I was doing the research. The 750 has the ratio ink-stamped on the back, but I have yet to remove the FT from it's housing to look for the stamp. Kawasaki may have used the same ratio, but from what I've read, Harley Davidson used a very different ratio.
Are the "universal" speedos programmable electronic units? I used a very inexpensive (and very light weight) bicycle speedo on my CB 750 with a magnet on one of the brake rotor bolts for the pick-up. The diameter of the front tire was used to program the speedo, and it worked very well, up to 72 MPH; it seems the processor in the $15 unit could only count that high. I've been told that other bicycle speedos are good to at least 100 MPH, and only cost a bit more. There are electronic speedos geared more for motorcycles, but they tend to be much more expensive.   
 

[scottly]

The ratio stamped on the 750 speedo is 2240 rev=1 mile.