ORIGINAL: Red B.
IMHO a nose ring for a .52 four-stroke engine is not needed. Could it be that the rubber bushings are worn out and need to be replaced? I have used the DuBro soft mounts on engines ranging from .46 OS two-strokes, .72 and 1.00 Saitos and also 1.8 Super Tigre two strokes. None of these engines has exhibited the behaviour you describe.
It is important to put some oil (castor is fine) on the rubber bushings when installing them in order to prolong their life.
Red, the 52 isn't a problem. It's my Mag 70 that is testing the mounts. Like you, I have used them on several engines and this is the first issue I've had.
The engine has had less than a gallon of fuel through it. The mounts were new on this engine. I did lube the bushings per the instructions when I installed them. I'm pulling down the engine mount this morning and I'll compare the bushings with another mount I have in hand. I'll post some photos.
Don