speedo drive ratio

deez · Post by **deez** » Sun May 04, 2008 7:58 pm

does anyone know the stock cb77 speedo ratio? im trying to change over to a modern speedo setup. thanks for any info

deez · Post by **deez** » Sat May 17, 2008 9:08 pm

This is how you find out what your tach ratio is

disconnect your tach cable from the tach body, make a piece of thin cardboard
about 3 inches long, stick it onto the end of the cable shaft ( punch a hole in it )

then take the timing cover off, put a mark on the rotor at 12:00, then spin the motor by hand until the rotor has made a complete revolution, count the number of times the cardboard hand went around....that gives you the ratio

EXAMPLE...rotor spins 1 rev
cardboard on the tach cable spins 6 times

you have a 6 to 1 ratio on the tach

havent had time to get this done but will post once i do, in the meantime if someone has the time to run this little ratio finder would love to hear the results.
cheers
-dee

deez · Post by **deez** » Mon Nov 02, 2009 7:24 pm

so im trying to put an aftermarket mini tach on my cafe build. i hooked it up and its the type where it connects to only one coil. well long story short its 2 rpm off. i hooked up the stock while this one was hooked up to find out. now my question is has anyone put an electronic tach or speedo with any success on a cb77? also i tried to find out tach ratio with formula above and i had to turn the rotor 4 times to get the tach cable to spin the cardboard once. so would the cb77 then have a 4 to 1 ratio? also when turning the rotor does 2 full revolutions equal one?
thanks for any insight
-cheers
-deez