I would take a step or back.
Disconnect cables from the carbs.
Check the twist grip turns freely, with cables sliding back n forth ok.
Note which cable 'opens' the throttle, and which one closes it.
Check carb sliders lift up and down ok, by turning the centre pulley.
If you take off the return spring (by the throttle stop) everything should move freely with little resistance.
Note, if you are unsure of the open and closed positions, see which way the pulley rotates and returns to the throttle stop adjuster screw.
Also, I see you haven't yet connected the choke cable, just make sure that the 'choke-arm' (off the carb-pulley) hasnt got stuck against the airbox or something, that could the carb-pulley from rotating.
The throttle-OPENING cable runs UNDERNEATH the pulley and hooks up into the slot at the rear of the pulley.
When re-fitting the throttle cables, make sure the cables locate in the groove on the carb-pulley; it is fiddly but with the tank removed it is possible; sometimes a set of long nose-pliers can assist in locating the cable nipples into the slots on the pulley.
goodluck with it.
