Velodrome...and Irebo,
think of vibes as oscillations of an object in 3 different axis..X-Y and Z...ok..literally an object moving up and down..side to side, and back and forth.When the object changes direction..ie: up...then down...we have what is known as acceleration and deceleration and that can be measured in a time factor. IF we can slow down this time factor, the result is we "feel" less of a jolt...
Think of hitting an anvil with a ball peen hammer..hammer bounces back really fast..high deceleraton and quick acceleration back the other way. put a piece of rubber on the anvil and then hit it..hammer still bounces back..so the same amount of mass just changed directions..inertia reversal was the same..but the time factor was much slower..and it FELT alot different.
IN an engine, because of the different parts moving different directions we have vibrations in all 3 axis. The highest inertia reversal is of course, from the piston and rod changing directions. This is the axis where we would measure the highest vibrations. but because there are counterweights on a rotating crank..lobes on a cam , lifters going back and forth..all giving us inertia reversals in different directions. we have to deal with all directions. And what we want to do so we dont "feel" so much vibration..is slow down the acceleratons and decelerations. IF we bolt the engine down solid...we have the hammer and anvil thing going on. Now if the frame was big enough and heavy enough to overcome the inertias...that would be great and we would hardly feel a thing. BUt on a bike...we have very little mass..so the whole thing shakes. Due to the high frequencies encountered in these little engines, we might call it a buzz..now...where are the low frequencies?...the thing that cause mirrors shaking on a Harley and the throb so loved by enthusiasts. Well they have mostly all be already taken out by the heavy counterbalanced flywheel.(which the Harley does not have) and converted to higher frequencies for durabilities sake. I am not goin to go any further here...but lets just say in the industrial engine world, this is how we do it.
But that is another subject...now to the Barry Mounts.
These mounts absorb movement in all directions..but they best work in the direction of the bolt Axis...they have a steel sleeve thru the center, in which the bolt and washer tighten up against and this sleeve is surrounded by elastomers of various density so no metal to metal contact can me made. Which is the problem with trying to just put a piece of rubber between an engine and a plate..and then run bolts thru in the normal fashion..bolt heads and nuts still make the contact and transfer the inertia. almost no deceleration at all. Back to the mounts...to utilize the ones in the photo, a .750 hole is drilled in one plate, and .375 holes for the bolt in the frame. The plate with the large hole is sandwiched between the rubbers and the engine mounted to this plate in the conventional fashion. Now..on the Axis's , because these work best decelerating the movement in the axis of the thru bolt, then by putting different mounts on different axis's, they will aid each other in controling each others weak direction. Another feature of these mounts is..by tightening down more...or less..(squeezing the rubber), you can vary the amount of movement vs. the amount of vibration isolation. The 2 plates can be as far as about .400 inch apart..if not much pressure is put on the bolts, down to about .250 if you really wanna squeeze em. If I have explained this with any competence..you will understand that the tighter you squeeze them, the more vibration you will feel, and the less movement you will have from the engine.The looser, the less vibration will be transfered, but the movement of the engine might be too much to...say..to throw a chain out of alignment. But that generally only will happen in all the mounts are in the same axis. And they dont have to all be 90 degrees from each other...just a few degrees...say 10 or 15 will do alot. AND...even if they are all in the same axis, and it is the same axis as the piston travel...you still will get a ton of isolation...and comfort.
