Don't have experience setting up GV-1 with 8U, but it shouldn't be any different from any other radio we have setup before i.e. 9CHP,14MZ,DX7. Have you followed the instructions in the manual.... u need to run through one menu in GV1 which is to set/calibrate your throttle positions i.e. at idle, full throttle and engine cut. Once setup, you can test it via another menu to verify that GV1 has stored/ memorised those positions correctly. This setup process is vital and make sure you get it done correctly.