Topic: Speedometer ratio for 75 CB750F

[jwk1414]

I'm looking to upgrade to stock speedo/tach on my F to something a little sleeker.  I found this little guy on parts-n-more http://www.partsnmore.com/images/parts/480/03-0744.jpg (part #03-0744) and found out via their tech department that it runs at a 2:1 ratio.  I've been trying to find what the stock setup is on mine but haven't had any luck- any input on whether I could use this speedo?

[david 750f]

From the FAQ's.

CB750 Speedo  2240:60  Tach 4:1
CB650 Speedo  2240:60  Tach 4:1
CB550 Speedo  2240:60  Tach 20:3
CB500 Speedo  2240:60  Tach 20:3
CB400 Speedo  2240:60  Tach 20:3
CB350 Speedo  2240:60  Tach 20:3

Edit....I believe the three most common speedo ratio's are 1:1, 2:1 and the 2240:60. 

[jwk1414]

ahh. don't i feel silly now.... Thanks David.

[KRONUS0100]

am feeling stupid now.....................what does the 2240:60 mean?

[geminimotors]

37.33:1

[david 750f]

I believe it means 2240 rpm at 60mph.. If you do the math it works out to approximately 1.7:1.
The easiest way to check would be to rotate the front wheel once and see how many times the speedo cable rotates..

[Dusthawk]

Thank you for this info, I asked for Tach ratios in a thread last week but this answers it for me.

[geminimotors]

Cyclerecycle sells those speedos and tachs in the ratios we need, but some are out of stock. http://www.crc2onlinecatalog.com/Index_Main_Frame.htm