Reply To: GT650r repair manual
Strange but here in UK the rear is hotter due to fact it gets less air (ironically not an air cooled bike but benefits from jet enrichment on the rear). Every twin hyosung i have worked on always had a rear cylinder 2.5 steps above the front.
Your setup with the customizations will be okay with a 127.5 range to 132.5 max size main jet on each cylinder. And this can be verified by plug chops that you will do just to make sure mixture is good.
The oem sizes is correct for 125 and 122.5 but rear should have had the bigger jet.
Did this help ? 🙏