Yes sir, please do detail the mounts used with clear snaps of your work. A cookie for the effort.
philcred, I do realize that the Marin's down tube is not round, so a perfect fit would be hard to gain. Take what I have posted below for what it's worth. I like your ride very much. In about two weeks my Specialized hardtail will be posted here and I doubt it will present itself as well as Marin.
I was going to note this elsewhere but will offer it now.
As an old mechanic I do know a thing or two about re-engineering.
If I ever use one of these Chinese engines(i just might at sometime) the mounts will fit the frame exactly. This will be done by using brass shim stock cut to size(brass is easy to cut and wear resistant). Upon second fitting, the shims will have a light layer of silicone adhesive applied, as well as to the aluminum of the crankcase and frame member. Then all would be tightened and the engine not started for 24 hours, to permit a cure. Excess can be cleaned off after the cure. Shim stock can be had by the packet that contains many thicknesses. All studs are up-graded because the stock one will/do break.
The clamps? I would use the best automotive exhaust clamp I could find of this type. I am suprised that I have not seen these used here already. Maybe someone has used them but not to my knowledge.
Only ONE thick washer would be used between the clamp and nut...I hate seeing stacks of washers. *sigh*
Nuts would be Loctighted.
The threaded bit is not used..only the folded metal bob part. Bits & bobs.