Reply To: Bike Can Only Start If I Rev The Throttle – GT250R 2013
Sounds like your TPS needs checking (throttle position sensor) and your Idle Control Valve (idle Stepper Motor) = These help regulate idling on the bike.
Check engine clearances (are valve clearances too tight?) or check engine compression too.
This topic below could help, as it goes in more detail on the EFi system
Check the ECU for any error codes, see the manual below to get error codes or “how many times the Red FI” light will flash, see below:
[Download] GT GTR 125 250 R Comet Carby & EFi Service Manual & Hyosung Owners Books