This may appear to be a no brainer question, but here goes.

I just purchased a Saito 180 for my 72" Katana, is the stock motor mount ok for this motor?

Or should I get a metal low vibration mount?
The plane is rated for up to a 140 4 stroke.

Thanks in advance

If the plane is rated for the size engine that you have purchased, then it should be just fine. If you are over powering it a bit, you may want to up size your mount. As for the metal mounts, I think they do not offer enough give in the event of a crash and you suffer more engine damage. Just my thoughts, Good Luck, Dave

The 140 4-stroke that the plane is designed to handle is likely a YS, which is comparable to your Saito 1.8. If the mount will handle the YS, it should also handle the 1.80.