Dave,
it sounds like the outer cable is too long, so you can modify it yourself by shortening it. Try cutting the outer cable carefully with a hacksaw, without damaging the inner cable, replace the steel ferule and adjust until you achieve the return you require. If in doubt, give me a call towards the weekend and we'll have a look together.
Having discussed getting his bike running better earlier on with Dave, can anyone suggest a good electronic ignition kit suitable for the D7? Any problems found fitting one?