Topic: speedo ratio

[ksrebel]

76 cb550k  anyone know the speedo ratio?  Did it change to something different in 77 or 78?  Can a cb750 speedo work in place of original?

[SKTP]

I think that I had a 550 tach on my 750 (eBay purchase). My Rpms read way higher than there were. I was a beginner motorcyclist at the time and took the bike to my mechanic complaining the bike was so slow. He took it for test drive, told be the bike was fine and to ignore the near red-lining tach. That's when I learned about the power-band and "feel". I can't be 100% sure it was a 550 tach, it sure looked the same as a 750 one. I later replaced it. This was about 8 or so years ago. I'd like to know the ratios too. I'm running s black bomber speedo right now and it's very wrong, although, the tach and odometer seem to be fairly close to accurate?!

[david 750f]

Speedometer ratio's are the same. Tach's are different.



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

[Powderman]

Doesn't this chart show that the speedo drives ARE different? Or were you referring to the year differences and not the 750/550 model differences?
A 750 speedo will not work.

The chat shows specifically the sped ratios are the same. ONLY the tachometer ratios differ. Go back and read the chart.

Speedo drives are based upon the hub, not the cam.

Sorry, i was reading the chart wrong.

[jonda500]

I got a cheap aftermarket cb500/550/750 speedo/tacho set for my 550F, the speedo works fine but the tacho only read about halve of the actual engine revs - I had to get a used oem cb550 one!

I would think a black bomber speedo would read a little low on a 550/750 with a 19" front wheel as the black bomber has an 18" wheel. Might cure the optimistic readings honda speedos tend to give you!
Black bonber(cb450 DOHC) tachos will work on 500/550's but have extra idiot lights you don't need,
John

[RAFster122s]

Unless you drop the cb650 camshaft into the cb500 or cb550 for more power and then you can use either the mechanical cb650 tach or cb750 tach Provided you replace the tach drive gear thst goes with the cb650 camshaft. Or, you skip the mechanical tach and use an electronic tach.
David

[DaveBarbier]

There's a lot of tachometer talk in this thread. The OP didn't mention tachs at all, haha.

[ksrebel]

Thanks for the help.