Tachometer jumps to 5K, couldn't find any info on error

[keratos]

sounds like it is the Throttle Position Sensor in setup mode. Unplug the wiring loom from the TPS on the side of the carbs, clean the contacts on both loom and TPS terminal side using Contact Cleaner

Then turn on ignition whilst TPS disconnected, then reconnect TPS still with ignition on then turn ignition off back on and restart