Not had a throttle cable break but a clutch cable caused a problem one year on the Dartmoor run.
Thats a good reminder to add a mole wrench to my kit which has 2 pairs of pliers to fit a clutch cable strapped to the bike under the petrol tank.
Altering throttle on mine, i would have to raise the throttle stops a little but not so easy with 3 carbs.