14T sprocket vibrations/shaking

WetDuc · February 19, 2010, 09:33:50 AM

For those of you who have done the 14T mod, did you notice the bike felt like it vibrated more? I seem to notice a spot around 4k rpm where there seems to be a rhythmic vibration. I thought at first it was speed related, but instead it seems to be an rpm range. I checked my chain tension and wheel alignment twice and all looks good. I'm wondering if anybody has noticed similar behavior after the mod, as this didn't start happening until after I put the 14T on.

Spidey · February 19, 2010, 09:35:22 AM

Set your chain so that it is a bit looser than spec and see if it helps. I can't seem to run my chains at factory settings without the sort of vibrations you're describing.

WetDuc · February 19, 2010, 09:51:45 AM

Right now it's set at about 27mm, so I will try loosening it up to about 30mm.
I find measuring the tension a bit weird since the chain hits the underside of the swingarm when pushed up so I don't really know the full travel upward, just downward.

ducpainter · February 19, 2010, 10:02:40 AM

Quote from: Spidey on February 19, 2010, 09:35:22 AM
Set your chain so that it is a bit looser than spec and see if it helps. I can't seem to run my chains at factory settings without the sort of vibrations you're describing.

even more critical if you have raised ride height.

WetDuc · February 24, 2010, 10:37:56 AM

I realigned my rear axle and checked the chain tension and I'm still getting the vibration. Later today I will loosen up the chain even some more to see if it takes care of it. Those axle alignment plates are so useless it's a joke. I don't know why they even bother putting them on when they bend the first time the axle nut is loosened.
I'm going to measure the axle from the pivot point on the swingarm this time to make sure it's straight.
I'll post up after this adjustment. For the ride home today....vibrations...

victor441 · February 24, 2010, 02:54:39 PM

no change going from 15t to 14t in my case.....you did check the tension in several positions, right??....sometimes the sprockets are out of round and can make chain tension vary considerably which can cause vibration

WetDuc · February 25, 2010, 02:53:18 AM

Instead of getting to do the adjustments, it rained 40F hell all afternoon and night yesterday. Hopefully, nature will give me a chance to work on it today. I'm not fortunate enough to have a nice garage to work on the duc in.

duc996 · February 25, 2010, 02:56:38 AM

No vibrations on mine,i will try to feel for it next time i ride though.

WetDuc · February 25, 2010, 03:28:22 AM

You would feel it pretty obviously if it was I am talking about. It's audible, rhythmic and has a vibration associated with it. Noticed most in 2nd gear 3k-4k rpm then in 4th and 5th same rpm range. Usually more noticeable when in a turn or under steady uphill acceleration, not fast hard acceleration (that takes it right past the rpm zone that causes the vibration and the bike feels pretty normal).
I'm wondering also if it could be a tuning thing...but have no idea.
Since it just popped up when I put the sprocket on, I really think it's somehow related.

loopsrider · February 25, 2010, 04:26:10 AM

Why not put the 15 tooth back on temporarily and see if the concern goes away? At least then you would know if you are headed in the right direction...

WetDuc · February 25, 2010, 06:29:29 AM

I thought about it...the 15T just...sux. I would hate to have to ride it with that on. More teeth on back, sure, but the stock setup is bad.
But yea, maybe I might have to do that...

LA · February 25, 2010, 06:38:12 AM

I've used 14t fronts for over 45,000 mi. now and never noticed a problem of any kind. Love em. And I've always kept the rear ride height an inch taller than stock.

LA

118811 · February 25, 2010, 06:55:23 AM

Quote from: iamhybris on February 19, 2010, 09:33:50 AM
For those of you who have done the 14T mod, did you notice the bike felt like it vibrated more? I seem to notice a spot around 4k rpm where there seems to be a rhythmic vibration. I thought at first it was speed related, but instead it seems to be an rpm range. I checked my chain tension and wheel alignment twice and all looks good. I'm wondering if anybody has noticed similar behavior after the mod, as this didn't start happening until after I put the 14T on.

I just switched to the 14T, and I too noticed a hum or vibration at speed.
Mine doesn't seem to be rpm/engine related..it is still there when I coast.
I think mine is the rubbing of the chain on the swing arm guide.
It has been about 3 weeks I don't really notice it now [moto]

Howie · February 25, 2010, 12:45:09 PM

If in doubt, loosen the chain a little more. A chain a little too loose will not hurt, a chain a little too tight can cause damage, and may even damage the output shaft bearing, which is a major repair. It is common for do it yourselfers to make stuff too tight.

WetDuc · February 25, 2010, 02:36:10 PM

I spent my spare time exhaust can chopping tonight. I didn't loosen the chain yet to see if it helps.
Will report back tomorrow after I git r don. I'll be aligning the rear axle from the swingarm pivot.

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14T sprocket vibrations/shaking