Re: Gravity or siphon gas line
Yes and no. The steel bushing running through the rubber on a motorcycle mount is slightly longer than the rubber. The through bolt locks tight to this bushing and essentially
Floats in the rubber sleeve.
Neither here nor there.
The fact remains that a dampener of sorts is needed.
Thin or semi ridged is best.
On a mountain bike build where the China Girl mounts don't fit the frame geometry.
I machine UHMW mounts that replace the rear block and are tailored to the front down tube.
Metal on metal is what I avoid.
But the engine must be solidly mounted.