I've used the iso-mounts before. On larger engines they
work ok. On smaller engines the improvement is not much.

I found that to get the most effectiveness, they needed to
be lightly tightened, but then there was trouble with the
rubber wearing through, or the nut breaking free from
the rubber.

The small ones seem to help most on 40 to 60 size
two-stroke engines. I didn't try the large ones.
My biggest engine is a 91 surpass. It ate through
the rubber on the small mounts pretty fast.

I used to have a source for even smaller ones,
but I don't remember where. After several
failures I gave up on them.

Jenny