ok, so does anyone else think that the way to set the timing on the hawk is one of the dumbest thing ever?

i recently upgraded to manual ccts, after doing it the wrong way and having both cylinders jump timing, ive reset them to what i think is right however, the rpms break up at about 7.5 8k and on decel i get noticeably more backfiring,

so first is there any insight to this,

let me tell you what i have
*clean air filter - stock, but not new
*shortened 2 bros exhaust (cut about 10 in. out of each)
*compression - 165 front and 163 rear
*new ngk iridium ix plugs
*never removed anything past the air box, never touched the carbs i did unplug the tps but never removed it
* ape ccts, set tension the new way by measuring deflection in the chain


so, i'm wondering if you have any suggestions or if theres a easier way to set the timing than what the service manual calls for

thanks in advance