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I’ve put a small thing suspension shim between my mount and engine to let it slide a little better. Makes it feel a bit softer. Also went -2nm on the torque setting.
And the actual resultant bolt tension from decreasing 2Nm will vary wildly depending if there's lube, loctite, anything else on the threads/bolt head, a new or used bolt, etc. etc.
The ENTIRE bike is flexing, from rear tire knobby all the way to front tire knobby, and everything in between.
I mean just about everything: Tire, tube, rim, spokes, hub, bearings, axle, swingarm, swingarm bolt, chassis, engine mounts, engine, steering bearings, steering stem, triple clamps, fork uppers, fork bushings, fork lowers, all through the front wheel again to the ground, all the bolts in the way along that path, and much more. And don't forget the suspension. Changing your tire pressure 1/10 of a psi will result in dramatically more flex change than adding a washer to the engine mount.
Not trying to pick on you, so please don't take it that way. But the placebo effect can be very strong, particularly with "flex" in rather small parts of the bike... When people make change that they believe will do this or that, they'll almost certainly come back from riding believing it worked. As a mechanical engineer, all this talk about flex drives me insane.
Will a motor mount made from a different material and a big hole in it make a difference? Yes, but not a whole lot. You're talking on the order of a couple percent difference in a static sense when you take into account the stackup of everything that flexes on the entire bike. Now the loading is transient, so the flex comes at different times in different magnitudes from different areas of the bike, so things get a little blurry considering that. Which is likely why the motor mounts might make a noticable difference.
For a reference datapoint, our KTM triple clamps are 33% stiffer vertically (bump direction) alone. But when you consider the stackup from only the fork lower tubes through the forks to the chassis, that drops to only an 11% difference. And that doesn't include the fork lugs, hub, axle, spokes, rim tire/tube, chassis, and the entire rest of the bike's deflections. Or the suspension itself. Can you feel the difference? Yes. But not because it's stiffer in a "flex feel" sense, but because it better keeps the fork tubes aligned resulting is less binding throughout the stroke, and an overall softer feel.
repeat for 4 motos, then do the same time at different tracks- have the friend take a log book where the rider is blind from the mount being used and note down the handling differences and get back to us with the unblinded data. LOL.
I once read at the peak of the Festina cycling team doping, Richard Virenuque heard about this new wonder drug for elite performance.... he complained to his trainers they wernt using it, so the trainers said they found some and gave him some vitamin pills. Of course, he was convinced with the new drug he would win, and of course he went out and blew the doors off everyone!
The average novice guy who rides every other weekend doesn't even check his sag but once or twice a year and many of them don't check their tire pressure before every moto, if they do at all when they get to the track.
Placebo or not if it feels better then it’s working the rider.
Shims, engine mounts and torque settings... Don’t knock it till you try it. I’ve been very surprised on little things that change the feel of the bike.
I was offering the OP an option to gain comfort on the 19/20 frame, since there’s no mounts available. Give it a shot and let us know if you feel a change.
Pit Row
Went through a book from a multi time world champion, when he was racing for a factory team at one point they suddenly could not close the door to his van when a practise bike was loaded up to be taken to the workshop. The new bike went in fine but not the practice bike. They took a part the bike and measured the frame and it was if I remember correctly 10mm longer, the frame itself just.
Steve mattes has mentioned that the Yamaha frames stretched around 6mm in first couple of rides when he was wrenching back in 2000.
I know for myself when I move parts between a new and old bike from same generation that it can be quiet tricky to fit certain parts. Typically one place you see it after 100h+ is that the gap for the exhaust pipe does not close down as it does when it is new (right around the shock). 3-4mm difference. Take a new pipe and same problem. Mount old pipe on new bike, no gap.
On topic of mounts, do carbon fiber mounts let it flex more or less? They are pretty simple on my bike and was thinking about making a set of carbon ones for it.
Any real change in feel is going to be altered by three primary modes of flex in the engine mounts - longitudinal bending, lateral bending, and torsional bending. The latter being the most important, or at least the one being the most addressed, which is evident by looking at the mount geometries (stock and aftermarket). By changing the geometry, you can easily reduce stiffness in torsion and lateral directions while increasing it in the longitudinal direction. So it's not as straight-forward as saying one mount is stiffer than the other since there's direction involved.
Now something that's carbon fiber specific is the importance of fiber orientation. This seems to be overlooked in the motocross industry, which is a bit silly really. It speaks to the rather basic level of engineering being applied in the moto world relative to things like auto racing, aerospace, and even bicycles.
Most people are familiar with the "standard" 1x1 plain carbon fiber weave. It's the generic look to carbon that everyone seems to think is really cool. Pretty much any carbon motocross part is using this weave. But the beauty of carbon is the availability of different fiber patterns that can be used to tune stiffness in different directions. Different weaves are available holding the fibers in different direction and a unidirectional "weave" is all the fibers oriented in one direction. With carbon it's possible to make a part incredibly stiff in one direction and rather flexible in another. When companies catch on to this and actually understand it, performance will improve rapidly.
But for now, particularly with engine mounts, I have yet to see any real engineering applied. It's copy stock, make a big hole in it, maybe change the fronts to titanium, and most importantly anodize everything a cool color. They're certainly testing different versions and iterating based on that, which is an engineering process. But there seems to be a lack of engineering fundamentals being understood. Stiffness is certainly changed, but in what direction? How much? How do these changes affect the ride of the bike?
Makes me want to make some engine mounts... But I've got too much on my plate as it is!
..make sure you get the holeshot or a good start at least so you can fade drastically in practice moto 1.
If anyone asks you what happened...... blame it on setup setup setup...
Before practice moto 2 ....(this is key) make sure NOBODY is watching you and secretly go back to your base setting "Home Base" as MC used to call it. Make sure you don't tell anyone! (Also key) I mean you're trying to win practice moto here so don't give away secrets ........yet.
Line up for Vet PRO Practice moto 2 which starts whenever you're done recovering and telling lies back at the truck usually...... get yourself a top 5 start, put your head down (but still look ahead) and charge to the end of practice moto 2 which varies between 2-10 laps depending on physical conditioning. When it's over....look around and do a fist pump because you won! When you get back to the truck .....proceed to tell anyone that you can, "I went back to my base setting and it made all the difference"
This is the key to winning Pr Vet Practice moto racing.
A1 "EXC Soft" & "A2-EXC-R Intermediate Flex"
https://www.cdgtech.com/product/ktm-engine-hangers/
And we've developed some VERY stiff mounts for the likes of BB4...'cuase, he get's what he wants! (A4 & A5)
Would love to try stiffer than the aluminum ones.
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