Reply To: GT 250 valve shim size? Forums 🚥 PiT STOP 🔧 Hyosung Technical Help GT 250 valve shim size? Reply To: GT 250 valve shim size? Oct 23, 2022 at 11:33 PM #8919 JimMember Topics: 11Replies: 142 I went with these Taiwanese made shims. I won’t check valves for a couple more weeks though.