Rattling Sound...Ideas?

[gsatterw]

Ok this one is a toughie.

When I hit bumps at pretty low speeds with the clutch pulled in I hear a metallic low frequency rattling/banging sound. I can't be sure if it happens with the clutch engaged because the sound of the engine drowns it out. I'm pretty much positive at this point that it is nothing on the outside of the bike.

The sound seems to be coming from somewhere in the front end, possibly from the engine, but I'm at a complete loss. Pretty much every time I get off the bike, I shake different parts to try and make the sound happen, but I can't make it happen when it's not moving.

Bike runs normally, clutch sticks a little bit on start up for a second. Any thoughts?

Thanks, Graham

[Dizzledan]

Hitting bumps would indicate the noise has something to do with parts attached to the bike. Do a finger check of all the bolts, especially around the fork and exhaust areas. The noise could also be your forks, have you checked the oil level In them lately?

[BockinBboy]

What you describe sounds very similar to what I have found in other posts, along with what I have experienced.  I still haven't been able to pinpoint the sound.  I just know that it comes from the front end.

I found one of the post that describes maybe the same thing.. I know there is at least one more since this one too.
http://gstwins.com/gsboard/index.php?topic=59403.msg702153#msg702153

I hope somebody figures it out.

- Bboy

[pliskin]

Yea, I could be the same sound I have. Mine does it clutch in, clutch out, on the gas, off the gas. Pretty much anytime I'm moving. It happens on slow speed bumps but I could be all the time and I just can't hear it at high speeds with all the wind noise.

I've done:
-New front springs/oil
-removed side faring
-removed gauges
-removed and inspected tank
-removed airbox
-removed battery box
-removed mirrors
-adjusted head lamp
-inspected brakes/lines/wires/cables
-inspected every other nut and bolt I could find

I still have the clunking sound. That stinking, nagging, rattling, banging, knocking, clunking sound is drivin me insane

[BockinBboy]

Yes, I have really listened for it since and I notice that it is all the time to too.  I think other noises just cover it up once I get going like wind, traffic, engine, etc...

- Bboy

[gsatterw]

Yea, I suspect its happening always. I've rattled every damn bolt on the bike, I can't figure it out.

[jestercinti]

Try taking off the stator cover and check for bolt tightness.  Maybe one of the clutch spring bolts is loose?

[Dizzledan]

What exhaust do you guys have? My Vance and Hines doesn't have the center stand spacer, sometimes ill hear that when going over a bump. Maybe some foam rubber where the stand meets the frame/engine.

[adidasguy]

Possible sources of a clunk when hitting a bump:

1. Gauges: rubber dampers around them hard, dry
2. Tank: there are supposed to be bumpers under it on the sides. Might be hitting the frame
3. Battery bouncing
4. Side stand or center stand missing a spring (each has 2) and bouncing against the frame
5. Chain bouncing against the swing arm or center stand (chain is loose)

[BockinBboy]

Okay guys, I think I pinpointed my sound.

After changing my springs (Woot for Sonics!) and oil in the forks, I wanted to be mega detailed on the entire front of the bike in torquing everthing to spec because of this sound... while I had it all apart.

I even replaced the little punch typed plastic tabs which hold parts of the fairings together.

Sound was still there, if not more rattling with a quicker pace.

Well, after driving my thoughts into the ground on this, everytime I rode I paid attention and made a quick note about it.
After review of my quick notes, it was clearly louder driving to work in the morning than driving home in the afternoon.
My first thought was temperature difference.  Right now, is about 65 in the afternoon, and 35-40 in the morning around here. So I wanted to first focus on everything that would change with temperature, starting with rubber or soft plastic type of things (harder in colder/softer in wamer was my thinking).  Tank rubbers fine/not the right area.  Same story with seat rubbers.  Had to look more toward the front, and the only thing else I could think of are the fork dust seals...

Turns out, the dust seals are dry and 'sticking' to the fork when they meet the max and min of each bump.  Which is also creating some brief hesistance in the front end on the bumps, and consequently, making this sound over bumps.  This is also why the sound 'sped up' when I upgraded springs.  The dust seals don't even look bad up close, i.e. no cracking or breaks in the surface, feel flexible... probably just near the point where I may start to see that.  So its probably a good idea to replace them before something gets beneath the dust seal, or part of it comes off and ends up ruining my fork seal. 

But, is there any way to lube this area to prevent that for the short term and extend the life of dust seals in the future?
I know on my mountain bike forks, there is actually a little foam/felt type of ring just under the dust seal that acts like a reservoir for lube that keeps the friction down.

- Bboy

[gsatterw]

I actually just figured out my sound: the chain was slapping the frame. Went away after tightening it up.

[adidasguy]

Fork dust caps are rubber. They can't rattle.

Most likely if the front:

1. Gauges rattling in  the holder
2. Front fender rattling  against the forks (there are rubber cushions between the fender and forks)
3. Loose exhaust header bolt.
4. headlight assembly

Chain is a good candidate.
How much preload on the forks? If you didn't have to push down the caps when you screwed them on you don't have preload so your springs and spacers are rattling.

In the event you didn't know: Oil goes in with fork compressed. Springs and spacers go in with fork fully extended. Typical spacer length would be even to 1" above the top of the fork tube. Then you press down as you screw in the fork cap.

[BockinBboy]

Its not really a rattle. It just sounds like a rattle when the forks go up and down and the dust caps 'stick' to the fork tube at the peaks when it changes direction.  The sound of the release of static friction from rubber on a metal tube over and over quickly.

Double checked and triple checked the spring procedure - Your comment made me look over it again just in case
Also, my chain has recommended amount of 'sag' - check this everytime I lube it.  Which is about every other tank.

- Bboy

[adidasguy]

Then there is a reason for leaking fork seals: they lubricate the dust caps 

Spray a little WD40 on the tubes or smear a finger's worth of fork oil.

Can we hear/see a video of this phenomenon?

[pliskin]

Same exact thing here. Cold= sound. After it warms up a little not so much. I'm thinking you are right about it being the dust seals. The only thing that is certain is that the sound is coming from the forks. I have had everything else that can be removed from the front end off and still have the sound. I'm going to pop the dust covers and see if I can put something like felt soaked with fork oil under them and see what that does. Something to keep the metal/rubber friction down.

Anyone know how to remove the dust covers?

[BockinBboy]

Just be careful not to get any particles underneath the dust seal that would cause a problem with your fork seal.  I mentioned the felt type ring on my mountain bike forks, but I've been hesitant to do that here because I'm worried of frayed edges of felt getting into the fork seal.  I'm truly not certain how 'touchy' they are.

I was thinking about some of the posts I've seen about this, and no one could quite describe the sound.  Not quite a rattle, or clunk, or bang, or cling lol... Its not really a plastic on metal, or metal on metal, or plastic on plastic type of sound.. but after I thought about the temperature, made me think of rubber on metal 

- Bboy