I have been working on a KF 4 with 912ul. Up to recently running well and still does over about 3000 rpm. At around 2000 engine becomes rough and then stops due to both carbys flooding. Both carbys have been overhauled so ok. It leads me to the engine mounts. They seem very soft and not that old. Is it possible to get a harder compound? They seem way too soft. What would happen if i shortened the bush on the bolt a bit to put a bit more compression on the rubber ? Any thoughts from anyone and is this a common event.