Twin cylinder shakes

[NoTies]

The engine on Nightcap is a Yanmar 2gm20. The thing does it best to leap into the quarter berth and beat its way through the hull at idle, typical 2 cyl behaviour. I'm not very familiar with small engine/flexible mount combinations. What recommendations are out there? Harder mounts? If so, how hard?
The engine is new with only 300 hrs on the clock. Living with it is not an option as the water p/p pulley is hitting the bearer when this happens. Also, I'm about 400 kilometres away from the boat so am not able to eyeball things right now, just trying to get my worklist together for March.

[BC Mike]

Go to Yanmarhelp.com there is an article on mounts.
Michael

[NoTies]

Excellent site thanks Michael

[Alan Wheeler]

Pete, unless you are sitting on an Iceberg, I think that should read 4000km.
But anyway, the wee Yanmar should run pretty sweet. However, there is a specific engine mount for this and all the yanmar models. It maybe your are either wrong or have been damaged. I know the Yanmar guy pretty well. I can ask any questions, but I can't think of anything in the way of answers he may give, apart from, replace them.

[never monday]

General recomendation for Yanmar mounts on a GM is a 5 year replacement cycle.
I'm reading that your engine is new and only has 300 hrs on the clock. I'd venture a guees that the mounts a) are in the wrong place, b) the idle is set to low.
The mounts are moulded with a numeric value on the side. The larger number on the front mounts and lower on the rear. Run up the RPM to around 1000, she should smoth out. It's common for the tach to be off a few hundred RPM. If you use a strobe then you can calibrate the tach with the screw on the rear side. There is an area of speed typicly 1700-2100 that it realy shakes. This is a dynamic of the 2 cylinder. Don't run there. The little GM's love to be reved 2800-3200 cruise with a one hour rating at 3600.