Here something I found out when adjusting throttle cables.
The 2 cable throttles on the new bonneville range is a push-pull arrangement with a return spring on the carby throttle shaft, if both cables are adjusted taught at the carbs then the push/return cable can be adjusted finger tight, at the slack adjuster near the throttle, so that when you apply throttle it stays at whatever position/revs required and to back off simply turn towards idle.
This overtight adjustment of the return cable negates the tension of the throttle return spring on the carby's throttle shaft.
I do not condone this practice, it is up to the individual to try it, just passing on my thoughts.
Cheers........Agro