Easier way to check. Pull the throttle then reach down with the other hand and see how much more the arm will move. It should have very little left to move, if any at all, and still have a little slack in the cable when you let off the throttle.
Cable will not cause a lean condition.
Another question. When it revs to 7k, does it feel like the impeller is slipping, or does the ski jump each time the engine surges ?
If it's been a while, the carbs really should be rebuilt. They can get all sorts of junk in them just sitting, even for a short time, and cause all sorts of problems, also check and make sure the carb mounting bolts are tight. If not, pull the carbs and make sure the are still gaskets there.
Good thing is, it's a 951 reed valve engine. Very good setup. While your in there, look and make sure all the oil injection lines are still soft, flexible, and secure. if not, now is the time to replace them.