Horn works only above about 2000 rpms

[cdh.fzr600]

I have a 94 FZR and my horn works but only if when you have the engine revved past 2000 rpms. Anyone know what could be causing the horn to not get enough power to function when idling or when the ignition is on without the motor running?

[mossy1200]

I think you may find the voltage is low and until the alternator lifts the voltage horn not going.
Turn you ignition on and test voltage standing and not running.
then test the voltage at idle and then 3000rpm.
you should get running figures idle 12.8 idle no lights with light on 12.4 (approx only) 3000 will be 13.2 and 13 (approx only)

if you got hard starting will be faulty cell in battery

Battery ignition off should be 12 - 12.4

[cdh.fzr600]

Where is the best spot to check the voltage?

Also I have found out that the horn works only from 2000-2500 rpms and let again after 4000 rpms.

[shredex]

maybe loose wire and the vibrations are screwing it up.
check your battery first.

[cdh.fzr600]

The wiring was all fine. Turns out it was just a faulty horn. I replaced the horn and it works fine now.