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Edited Date/Time
9/25/2014 11:13pm
I see all these AL frame 2 stroke builds to modern 250/300 motors putting out a lot of vibration. You see rubber mounted handlebar products stock and not stock to curve the issue, but I have never seen a rubber mount that would reduce the issue at the source, the MOTOR.
Another motor that vibrates terrible is a V-Twin harley-davidson, they experimented in the 80s on a few models and went full on rubber mount on softails in 97, and most bike from 02 04 on..
I'm not talking about a mount with the durometer hardness rating as a tennis ball, but more of a boot sole rating.
I guess I'm more curious of the disadvantages? Thoughts?
Another motor that vibrates terrible is a V-Twin harley-davidson, they experimented in the 80s on a few models and went full on rubber mount on softails in 97, and most bike from 02 04 on..
I'm not talking about a mount with the durometer hardness rating as a tennis ball, but more of a boot sole rating.
I guess I'm more curious of the disadvantages? Thoughts?
#1 reason, its a competition motorcycle, the frame attachment points are a key part to frame flex and stiffness. couldn't achieve the same results if you rubber mounted it, just like you will never see a road race bike with a rubber mounted engine.
I would rubber any engine btw..
The Shop
When Zach Osborne was on Bike It Yamaha here in the UK i was told that not only was he very hard on motors (think a set of cases were shot after 3 meetings) , he could also feel the bike go 'off' if the motor mounts and swingarm loosened off. Wasnt unusual for him to come in and get them redone , and go back out with out changing anything else.
I cant remember who told me that , but i was commentating on him at the time , and it was someone who was in the box with me .
Could you weld metal engine mounts to an aluminum frame? And would that make any difference?
Pit Row
But i'm assuming by metal you are referring to steel? If so you can not weld aluminum to steel. Just for fun, if you welded say a aluminum case to a aluminum chassis, the weld it self becomes hard/brittle by the welding process, so a heat treat process to "normalize" the entire frame and case would be in order, in other words not worth it, plus getting around the motor assembly problem after
You wouldn't lose any torque, but would definitely lose chassis stiffness.
Cheers
Simon
Good question though I've wondered that as well.
I like dinosaurs
first of all, stiffness and power losses ARE absolutely the reason you don't rubber mount ANYTHING! There is not a racecar or a racebike on the planet with rubber between the powertrain and you. Formula 1 cars have the motor bolted right to the main chassis bulkhead (the drivers back rests right against that, with nothing but a thin carbon seat between them) and racecars made from passenger cars have every single rubber mounting point replaced with solid mounts.
Now, for the vibration issue. Just be thankful your not riding air-cooled open classers...they'll rattle your teeth out. Fortunately, there are many things that can be done to reduce the vibes. Most of them individually will not make huge improvements, but all of them in conjunction will. I hate vibration, I mean I really hate it, so over the years I've always been on the lookout for ways to improve vibration. . But just remember, you need a counterbalancer or multiple cylinders to rid all vibration. Things that only exist on quads, so...one more reason quads are for pussies.
Here is a list of things that will reduce vibrations
1. dynamic balance of the reciprocating assembly (crank, rod, piston) - unfortunately there are only a handful of places that can do this for single cylinder engines, one of them is The Crank Shop. This will eliminate more vibration than anything else. most knuckleheads think that truing your crank is balancing it. it is not. ..and static (mathematical) balancing is ok, but why mess with it? it doesn't cost anymore to have it dynamically balanced.
2. true your crankshaft. -assuming your crank has measurable run-out. Then weld the crank pin in place, which will require a fairly competent crankshaft guy, depending on how much clearance you have in the primary compression chamber, i.e. crankcase. This should be done even if your crank has been dynamically balanced or even if it is "true"
3. anti-vibration handlebar inserts. these work. plain and simple
4. rubber mounted handlebar mounts/clamps - obviously, this is why they exist.
5. as stated above- properly shim your engine AND your swingarm.
6. Fatbar type handlebars, Flexx bars, or any other bars with engineered flex.
7. cushy-style grips like ProTaper's pillow top.
8. loosen your white-knuckle-death-grip on the bars...there's no need.
9. race fuel...i'm not going to go into the why, but all you have to know is that it has nothing to do with detonation, which obviously makes things vibrate.
10. adding cushy insoles to your riding boots. no brainer there, although not all bikes and all people will feel vibes through their footpegs.
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