07 heritage? FI so it isnt vapor locked. Has to make a full cycle before firing unless you have an aftermarket ignition. Is it rebuilt to 10: or higher?
I will assume that by kicking back you mean that when you try to crank it, the starter engages but stops like it has a weak battery. But when you try again it will cycle through and crank?
Is the starter getting hot? Almost sounds like your charging system is going south. Has to be, battery, you eleeminated that, loose primary chain,compensator, or stator not fully charging. Did the 07 still have an inspection cover on the primary cover?
I went from an 01 to a 12 and realized that screws were missing when I changed to oil in the primary.