Volvo MD5B vibration. RPM sweet spot?
Our little 1985 7.5 horse MD5B runs smoothly at around 1000 RPM and 1500-2000. At other speeds, it vibrates. I mean vibrates. Under 1000 RPM it shakes the door to head loudly enough to drown conversation. Not to mention making the wife uncomfortable. This is all while in neutral.
I'm familiar with engines in general, but not so much diesels. Is this vibration normal in these single cylinder engines? I am suspecting engine mounts first, but are there other things I should look at?