Stewart's YZ450F Rubber isolated frame mounts...

Can't change the position with one of 4 mounts. It's not being done for engine vibration, as the top mount doesn't appear modified, and the rear mount would be pretty difficult to build an isolator into.

I would think they meant to say it's to give the frame more flex to affect turning and/or other handling characteristics.

Any flexibility in the mounting of the motor would allow it to shift backward upon acceleration and forward once the throttle was let off, like your ould V-8 flopped to the side when you gave it the gas. That couldn't be good at all. More likely the single resilient mount provides for thermal expansion or flexing of the frame.

Any flexibility in the mounting of the motor would allow it to shift backward upon acceleration and forward once the throttle was let off, like your ould V-8 flopped to the side when you gave it the gas. That couldn't be good at all. More likely the single resilient mount provides for thermal expansion or flexing of the frame.

It didn't bother the Norton Commando, and the later Harley's with isolator engine mounts are OK. Every car and truck on the road has rubber engine mounts. Race cars tend not to use them, but only because of the reliability concerns related to their tearing/breaking under the extreme stress.

I do think you're correct that this looks to be just the one front mount that's been done this way, probably to add the flex of the curved part of the cradle into the steering head. Something I wouldn't recommend, but....

"probably to the flex of the curved part of the cradle into the steering head"

wouldn't the main frame have to flex also in order for the lower cradle to flex? i'm having a hard time visualizing that much flex in the frame with so much suspension travel.

Don't get me started, OK. I have a kind of negative overall view of the whole idea that there's a benefit to actually encouraging the frame to flex. Doesn't seem to be well received.

And yes, your first assumption is correct.

"And yes, your first assumption is correct. "

it wasn't an assumption but a question,...to you

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