Fred,
There is a factory flex coupling in between the ST head and engine with a spider inside much like the LoveJoy type.
the coupling was really pretty nice for a stock Chineese type, BUT the spiders were junk,,,Too soft and kept breaking apart, I got some replacements, then made a mold to make my own out of high tech window sealant, finally replaced the whole thing with Lovejoy setup with band type spider which is replaceable with out moving engine or St head and loosing the alignment.
My 1115 really doesn't vibrate more than it should, the Murphy solinoid welds just gave it up after running more than a week 23.5 hours per day after Wilma came to kick our butt. At 1800 rpm the deep sound was nicer than my neighbors briggs units. I burnt 11 gal per day (23.5 hrs) at about 5 to 6 KW
My portable 1115 looks much different now, those pics were taken when I ran it (unfinished) for 48 hours after Katrina came and gave us a kiss before hitting New Orleans 4 or 5 days later.
Here's a link to the general photobucket album. I see I never uploaded picks of the finished setup, There are some pics of the factory and lovejoy couplings.
http://s217.photobucket.com/albums/cc153/Petersbpus/12KW%20Genset%20home%20power%20Diesel/Your setup looks really clean, I see a fuel filter heater, your burning WVO?
I'll be working on a method to shutdown with an over Hertz condition.
As far as linking shutdown to rpm directly, my impression is that may be somewhat tuffer, However you could install a toothed flywheel ring on the flywheel so you could count the teeth with an inductive pickup, tied to a tach, tied to the Murphy 117 tattletale you already have.
more than one way to skin the cat.
Bob P.
