Sweet Vibrations (919) - Wrist Twisters
 
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post #1 of 13 Old 04-06-2018, 07:08 PM Thread Starter
Tirone
 
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Sweet Vibrations (919)

Okay maybe not so sweet, they are wearing me out way too fast for a bike this otherwisely comfortable. Not just in the 4k-5k range but pretty much all over spots in the powerband I'm getting some pretty harsh vibrations that are wearing out my hands and feet pretty quick. What are the go to mods for reducing vibrations on the 919? Right now i'm down a tooth in the front from stock, (previous owner mod) though I plan on going back to 16t when i get the tires changed next week to get me out of the 4-5k rev range all the time. Other than the Renthal bars (gonna get to those) what are some ways to reduce vibes throughout the bike? What things could be causing such rough vibrations?

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post #2 of 13 Old 04-06-2018, 08:23 PM
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A broken exhaust mount underneath has been known to cause bad vibes. How many miles on your chain and sprockets?
Wheel bearings good?
I only get bad vibes in my left footpeg at about 4-5k. I'm going to try and add rubber spacers to the left rearset mount to reduce these vibes.

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post #3 of 13 Old 04-06-2018, 09:23 PM Thread Starter
Tirone
 
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I'll check the exhaust mount cause honestly that could be it. Bearings and C/S feel fine there's plenty of miles left on em though they could use a cleaning. Definitely gonna look into rubberizing those rear sets for that specific problem.

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post #4 of 13 Old 04-06-2018, 10:44 PM
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Yeah I'm going to order these and fit onto rearset mounts.
http://www.ebay.com.au/itm/183124857749
I just took passenger pegs off. I'll see if it makes a difference. Also placed some thin rubber cut to size under rearset mounts.
If this doesn't reduce vibes I'll bolt a lead plate to rearset at passenger peg mount. Try to dampen vibes.
It's only my left footpeg that vibrates. And only in a specific rpm range.
Good luck with reducing your bad vibes.

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post #5 of 13 Old 04-06-2018, 11:10 PM
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Go with the 17/44 set up. You'll be amazed at how much smoother it is.

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post #6 of 13 Old 04-07-2018, 02:17 AM
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I've got a bone stock setup and the vibration isn't that bad.

You need to find the problem. Some complain about a RPM spot on the freeway, the 17/44 just drops the RPM a bit.

I'd start checking the balance of the tires, chain slop, things like that, head bearing play...

You can check the front end by just lifting it with a floor jack under the exhaust while on a rear stand. The tire should spin free and not have any heavy spots. Head bearing should be smooth with no catch points or fore/aft play.

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post #7 of 13 Old 04-07-2018, 04:00 AM
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I've tried something else out tonight. I read this on another forum concerning Honda motorcycles and footpeg vibes. It's a fix someone else tried. While I don't know the cause of the vibes it's possible that it is from the drive train. Specifically the front sprocket and chain. This might explain why the vibes are often worse on the left footpeg. Honda's OEM front sprocket had a rubber dampener on it. To reduce noise and vibration?
Anyway the fix. First rubber washers on rearset mounts. Next add rubber inserts inside the actual footpeg rubber.
You take the footpeg rubber off. Undo two 8mm bolts underneath footpeg. You will see the rubber is actually hollow and will squash down easily. Using rubber strips pack this cavity. I used a exhaust bracket rubber. Lubed it up with little detergent and stuffed that strip inside. I used a second cut down piece to fill the remaining space. Bolt it all back together.
The idea is to put more rubber between your foot and the metal peg.
I'll give it a try out tomorrow and report back.

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post #8 of 13 Old 04-07-2018, 06:11 AM
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The type of muffler you're running, and the fuel mapping, can have an effect on vibration as well.

Most, but not all bikes don't need to be "geared down". <Usually, that's just stupid.

My carbureted 900RR, which is mostly the same engine, as your 919, is really smooth.

After I rejetted my little 599, and put a -2t sprocket on back, that bike, which has a nasty rep for being buzzy, which they are in stock trim; turned out to be quite smooth.

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post #9 of 13 Old 04-07-2018, 06:51 AM
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I remember reading somewhere, maybe on this site, that going down a tooth on the front sprocket can cause excessive wear on the chain. Because the chain has to work/bend more to fit around the smaller diameter sprocket. Possible it could cause some excessive vibes as well.
Make sure your chain isn't too tight and alignment is spot on.

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post #10 of 13 Old 04-07-2018, 07:27 AM
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I wonder if there's some way of you filming your bike in action. I've been riding mine for 5 years now and never ever had a problem with vibration from the foot peg area.

I really think you better find the real problem instead of trying to cover it up. If you cover up the problem, it's only going to get worse. If you have a GoPro, maybe attach it down on the swing arm.

Maybe run the bike on a stand and see how much vibration it has.

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post #11 of 13 Old 04-07-2018, 09:08 AM Thread Starter
Tirone
 
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Yeah I could mount my GoPro and see if it picks anything up. Everything seems to be dialed in fine other than the tires being worn out so when I get those swapped I'l make sure everything is fixed up and see what that changes. I have the stock 16t still and it does have the rubber on it which could confirm Islands theory. I'll also update the main post with the current exhaust setup but basically I'm running everything stock with a bafflectomy. So I still get the exhaust stink which I was gonna address with the PC3 and Slip-ons later when I had the cash to.

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post #12 of 13 Old 04-07-2018, 10:14 AM
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worn tires, especially if cupped, will cause vibrations in different places that respond to different harmonic frequencies. Start with your tires, then check your chain tightness and alignment.

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post #13 of 13 Old 04-07-2018, 02:33 PM Thread Starter
Tirone
 
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So I just sat and revved it standing still and I'm back to wondering about exhaust/engine mounts cause It was just as bad as moving. Just never focused on it cause I usually don't sit and rev at a standstill. Gonna try that footpeg insert though cause that will be nice regardless.

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