Tacho goes erratic above 8000 rpm - 1998 Honda CBR 600 F(3)W

run the fault codes
could be the vacuum actuator , TCM or ECM
take it to a specialist auto transmission shop for a proper diagnosis and quote

tachos get their signal from the coil or the ignition control module or ECM
check for ;loose / broken wires in the harness or at connections
There will be no fault codes for tachs unless it affects an adjacent sensor
could be a faulty tacho unit (tacho--tachometer--rev gauge --rpm indicator )

An r1 has a self diagnostic fault system, this is done via the tacho so I would say there is a few problems ,usually it will only do it when you first turn it on though.I'll see if I can find a manual and give you a link to it.
http://www.carlsalter.com/download.asp?p=1750

Not familiar with this model, but suspect crankshaft sensor when tach is erratic.

you have an in cluster factory engine tachometer (RPM)?
the tacho is meter in the cluster and does not use speedo parts or its cable.
its just a meter that needs power, ground and spark tacho signals
if all 3 are good, the meter is bad. period.
the tacho signal goes to the ignition coil minus lug, and will good, as engine runs. so... wires bad, to tacho or tacho bad.
ever price a new one? or even used? $100 used?
you willing to pay that much for just a factory tacho?

there is NO speedo cable. this old 93 is electronic, (rare on most 93 cars made, toy is advanced)
here is the proof, amazing how books dont lie....
there is a speed sensor.
the tacho and speedo use the same power and ground
leaving just one wire,r-g red-green RPM sig. pin 5 of cluster
an is SPARK primary sig. so if only tacho is dead.
then the tacho is bad, or that pin 5 wire is dead.
got you to just 2 possibles.

A/T tranny"drive"
are the brakes iced over.?? i can't know this. only you.

if not, ice, then tranny is sick
get help

do you have a dash tachometer? RPM?
this instrument tells you what is wrong,
1: Tacho RPM buzzes high bad tranny.
2: tacho rpm sticks at say 2000rpm not running free with right foot action that means the breaks are locked up with ice or hand brake is ON.

ever tune it up,?
carb engine, or EFI?
the tacho action tells you the primary ingition side is failing.
the jumper is inserted, in the EFI , code 8 is spark misfire.
jumper the service check connector , 2 pins.
code 8 can clear fast, so you make engine mistfire, watching the lamp. but is only more evidence that the the ECU can not fire the coil.
The Tacho proves that. if the code 4 or 9 show up, bingo.
drive with the jumper planted.
see page 6-96 in the FSM book.


http://hondatech.info/downloads/Auto/Manuals/Civic/