Gear ratios for speedometer and tachometer

Im looking at replacements for my speedometer and tachometer.

Its a 650G. What is the gear ratio for the speedometer and the tachometer if necessary (not sure if it is at this time).

And finally.....Im looking on Dennis Kirk. Not much of a selection in the Metric section...but in the Harley..will the Harley mechanical gauges work with my bike?

Thanks in advance for your responses!

D

 

It is my understanding that virtually ALL Jap bikes with mechanical speedometers use the same drive ratio from the front wheel, so even a Honda speedometer will work, but NOT A HARLEY. (We have "metric" bikes which Harleys ain't) Tach is simply RPMs so there really isn't a gear ratio per se. Cool item in regard to Yamaha mechanical instruments: The "guts" (the actual instrument body) appear to share shape and mounting points across most of the line well into the 90's (when they got smaller.) I'm in the process of transplanting speedo guts from a '79XS (120mph) into my 550 Seca to replace the "Reaganometer" (85mph) and it appears it will be nearly a direct swap.

 

Yamaha speedometers take a 2240:60 ratio to work properly. The 2240 = 60 MPH means that the cable spinning at 2240RPMs will read 60MPH. It's a calibration scale. If you increase or decrease the wheel diameter you'll have to change the speedo gearing to ensure that when you're actually going 60mph the speedo cable will be spinning at 2240RPM which will cause
the gauge to register 60mph.


The tachometer's 1:4 will read 4 RPM for every turn of the cable. I think. (I might have that backwards.)

NOTE: electric tachs take the measurement from the TCI, which actually sends a signal twice as often as is necessary (lost spark system), so the tach actually registers only 1/2 of the # of signals it receives.

 

There you go. I believe the 2240rpm=60mph ratio is common to all Jap bikes of the era, regardless of manufacturer.

 

Thanks for all the info.....Im just at a loss for what do to for gauges at the moment....just means more research and questions.

 

I have the speedmeter from a CB350 Honda on my 750 Seca and it is more accurate than the original stock speedometer. Just about any mechanical metric speedomter will work (Honda, Kawasaki, Susuki or other Yamaha) if you can find a way to mount it on your bike. Your speedometer cable should work with most of them also.

 

I have a speedo from an '86 FJ, FZ?
One or the other, I haven't had the chance to have it checked but, in traffic, highway, it seems to be right on.
It bolted right up, I used the rubber surround from the original because new one was ever so slightly smaller.

 

The 550 Seca has a "gauge cluster" and other speedos look like they'll bolt right in, too. See? I toldya there's more than one way to skin Ronald Reagan. If he only knew the lengths to which we go to exorcise his legacy from our classic steeds...

 

Ill keep looking. Ill eventually find something that makes me go...AHHHHH. Going to have to do it all online it looks...the only bike salvage yard I found an address for here in Oregon is closed down... grrrr.

 

dug this up but FYI 91-94 XL,FXR,FXD,84-95 FXST,FLST 84-86 FXWG harleys use the 2240:60 ratio also per J&P cycles catalog