Originally Posted by Flyman
Tom I agree 100 percent with that mounting solid. But to this day I never
understood why. Can you are someone shed some light on this for me.
Let me see if I can put this simply.
When you place rubber, or a resilient material between the engine and the frame the engine will then be allowed to move within the constraints of the rubber. That movement is then amplified and transfered to the mount fasteners, which are usually the first to fail. Another way to say it is the more the engine can move the higher the vibration.
Not only is this increased vibration then felt more in the frame but the stresses are more than the mounting system, as designed, can take.
Motorcycles and cars use a rubber, resilient mount but it is in effect a sandwich of metal, rubber, metal. This system will act as an absorbent to isolate engine vibration, movement, between the engine and the vehicle frame. There is no metal to metal contact.
When one just puts rubber between the mounts and the frame, without that sandwich concept, the engine is allowed to move more that it could and the vibrations are increased because of the movement. Every vibration cycle is then transfered directly to the metal parts of the mount, fasteners and frame and is felt by the rider and parts attached to the frame.
Mounting the engine solid to the bike frame doesn't allow the engine to move. Therefore the vibrations are limited, and distributed evenly throughout the frame. This reduces what you feel in the frame and handlebars and its effects on other parts.
If you have the opportunity, closely examine an engine mount used on a motorcycle or an automotive application and you'll easily see the 'sandwich' concept I described above.
Also keep in mind that most motorcycles and cars do not rely on a single cylinder 2 stroke engine for power. Those that do either used the solid mounting concept or a resilient, sandwich, style of engine mount.
I hope my meager attempt at an explanation helps.