FWIW, big inch, high compression engines build heat so fast when holding rpm/load/tp initial tuning is always a challenge as compared to a stage1 or 2 bike.
For initial tuning on older (non-closedloop) bikes I have found with some really big power added builds, assuring safe timing with the flash tuner and then using a PC to get fuel close in short timeframe works well to get some miles on it.
Then remove the pc and tune it to a tee.
Just my experiences,
Bob