Topic: 78 cb550k speedometer and tachometer ratios?

[jason teamshralp]

I have been searching and can find a few subjects for other model bikes but not for mine. So if anyone knows the ratio for my bikes gauges please let me know I have a broken tach cable and I'm using that as an excuse to buy mini gauges.

I have found some on http://crc2onlinecatalog.com/Index_Main_Frame.htm They have a general fitting guide, but I want to make sure before I order.

Also found some for cheaper on http://www.mikesxs.net/mikesxs-accessories.php?category_id=8.5 but they are for Yamaha's and I don't know what ratio they use?

all help would be great. Thanks.

[eurban]

Most of the 70s and 80s japanese bikes use a speedometer with the 2240-60 ratio.  The SOHCs use this ratio.  The speedometers from Mike's XS should work.  I don't know the tachometer ratio for XS or for the smaller SOHCs (it is most definitely not the same as the 750s) but it is 4:1 for the SOHC 750.  Check out Electropsort's collection of Acewell guages.  Tach and Speedo in one unit.  http://www.electrosport.com/street/speedometers.php


Hope this helps. 

[Clyde]

As eurban states for the speedo. Pretty near all speedos used that ratio and it is still common today
The tacho ratio on the 350(T&F),400F,500,550 is 20:3.
The 750 is 4:1

[martino1972]

how about the cb 650??
spotted some cool looking tack / speedo for my bike,but they are for a cb750..

[jason teamshralp]

does anyone know the tach ratio for a yamaha xs650?

also thanks for the replies above.

[Quartza]

The xs650 tach ratio is 5:1

[Helo229]

I ordered a set of gauges off Mike's for my 750F. Pretty good quality, I haven't had a change to run them yet since my build isn't finished. I recall while reading the ratios that a number of people have used the 1:5 tachs on their 750's without much complaint. Unless you're going to rely on it to shift and/or run close to redline I'd say it's close enough. For a 650 and smaller I would recommend going with a digital/electric gauge running off the coils. Mike sells one manufactured by timex for about 30 bucks more than a mechanical if I recall. If not there's plenty other available from all your car parts stores thanks to the Ricer revolution. Seems like every young punk with a Honda has to have an aftermarket tach in their automatic fart-can equipped civic.

[Sporkfly]

*bump*

Wondering what the tach ratio for the CB650 is. I'm thinking about dropping a 650 cam into the 550.

[Quartza]

I just got a 650 cam and tach drive gear.  The ratio is 4:1...which is great because I could never find a white face 7:1 mini tach

[Sporkfly]

Wonderful, thanks. It's good news because the tach I have on my 550 is from a 750 with a tach ratio of 4:1. APO mistake might actually be useful to my build. Now to find a 650 tach drive gear  .