Looking for a little advice... but I have a feeling the answer will be: "take it in to have a service tech check it out". Also, did a search, but didn't really find anything that described just what I'm experiencing.
Just did a sprocket/chain swap. DID ERV3 gold + geared down to a 14T front (from the stock 15T). The chain is properly adjusted (never overtightened) and the rear wheel/sprocket have been laser aligned. I also just installed a Desmo Times Case Saver and Billet Rear Axel Plates, put on a new SpeedyMoto Front Sprocket Cover.
Over the last few days I have noticed a strange harmonic whine coming from the left side. Somewhere near my left foot, so between the output shaft/front sprocket to the rear wheel/sprocket. It only becomes apparent at speed (usually 35+) and only after the bike has warmed up a bit or I've ridden 10-15 miles.
I initially feared the chain might be making contact with the case saver, but I took it all apart and no signs of any contact. Checked for obvious play in the output shaft (crank) and couldn't feel anything. In neutral I could spin it and I don't feel anything rough with the bearings. Some ever-so-slight lateral play on the front sprocket, but nothing out of the ordinary for the Ducati fixing plate system IMO. No abnormal wear on the sprocket itself.
I then I thought rear wheel bearings. Took the chain off and the wheel spins pretty freely. No rough spots detected there, either. No play in the wheel (that I could feel, at least). Also no signs of abnormal wear on the rear sprocket.
I just can't figure out what's making this noise. Very hard to pinpoint an exact source while riding the bike, too. Again, sort of a harmonic "whine" at speed. Gets more prevalent the faster I go.
Maybe the new chain rolling on the chain guide, now that the front sprocket has been reduced 1-tooth (putting it slightly closer to the swingarm)? A bearing that is starting to go bad, but not bad enough to feel just yet? I just don't know what else to check & I'm a little worried.
Does this sound familiar to anyone?
Any advise on my next step(s)?
Year and model would help.
If you raised the rear the chain may be rubbing with the 14 tooth, but before doing anything else I would back off on the chain adjustment and see what happens.
2002 750S i.e.
And yes, the rear end has been raised up... about 14mm if I remember correctly (it was quite some time ago).
Quote from: howie on April 23, 2010, 09:22:26 AM
Year and model would help.
If you raised the rear the chain may be rubbing with the 14 tooth, but before doing anything else I would back off on the chain adjustment and see what happens.
+1 Raising the rear means there is more travel in the swinger before the chain reaches it's tightest point so you need to give it a bit more slack to start with.
Quote from: Dan on April 23, 2010, 11:36:44 AM
+1 Raising the rear means there is more travel in the swinger before the chain reaches it's tightest point so you need to give it a bit more slack to start with.
Oh, that makes total sense!
Manual says 20-25mm. But I've been checking/adjusting while the bikes on a side stand or rear wheel stand.
Logicly it takes some travel to get the driveline to it's tightest point. So what seems adjusted properly on the side or wheel stand, could be too tight with me on board.
I will loosen her up and see what happens.
Maybe put my wife on the bike (plus my kids to aprozimate my weight [roll]) with it on the rear wheel stand and adjust it under load.
If you are over 160 lb. 20mm is probably too tight. I'm 185 and I adjust to 30 - 35mm on the side stand.
Quote from: 64duc on April 23, 2010, 12:41:25 PMIf you are over 160 lb. 20mm is probably too tight. I'm 185 and I adjust to 30 - 35mm on the side stand.
Oh, yeah... I'm well over 160.
Haven't had a chance to do a ride & confirm 100%... but right now i'm pretty confident it was the chain.
I managed to hop up on the bike (VERY carefully) while up on the rear wheel stand & reach down to check the chain while my weight was compressing the suspension. It was tight as a guitar string!
I loosened everything up again and adjusted again, checking the slack while compressed under my weight. Looks like it's set up right now, 20-25mm slack with me on it. WheN I'm not, it looks loose. 2-2 1/2 inches but that's just the way it's got to be.
Now I hope I didn't hurt anything too bad riding to work & back Thursday (about 30 miles round trip).
Quote from: msh441 on April 24, 2010, 04:16:24 PM
Oh, yeah... I'm well over 160.
Haven't had a chance to do a ride & confirm 100%... but right now i'm pretty confident it was the chain.
I managed to hop up on the bike (VERY carefully) while up on the rear wheel stand & reach down to check the chain while my weight was compressing the suspension. It was tight as a guitar string!
I loosened everything up again and adjusted again, checking the slack while compressed under my weight. Looks like it's set up right now, 20-25mm slack with me on it. WheN I'm not, it looks loose. 2-2 1/2 inches but that's just the way it's got to be.
Now I hope I didn't hurt anything too bad riding to work & back Thursday (about 30 miles round trip).
Your chain is too loose IMO.
The slack measurements given are for an unladen bike on a side stand.
If you raise the ride height you need to increase that slack, but not to the point of having 20-25mm when the bike is laden. You just need the swing arm to be able to pass the center of it's travel (the longest distance between the two sprockets) without going bowstring tight.
You'll grind holes in the engine cases with the chain that loose.
You can check what Nate is saying in less than an hour:
Raise the rear on a stand.
Remove the rubber caps from the swingarm axle (pivot side) and slide a 24" 1/2" dia steel rod through the axle.
Use two jackstands to support the bike at the rod and remove the rearstand.
Now pop the rubber cap on the swingarm and loosen the bottom shock heim joint. Tape the allen/socket/extension together so you do not lose anything inside the swingarm. You may need to loosen the top of the shock too.
Now swing the arm the full arc and notice how loose/tight your chain is. Adjust so it is free at the max extension.
Put everything back, then note the measurement on the sidestand for future reference.
Lots of ways to check, the goal is to confirm the chain is not too tight when the swing arm is parallel to the ground. That becomes your new spec. 2 1/2'' is way loose.
Quote from: battlecry on April 25, 2010, 04:51:57 AM
You can check what Nate is saying in less than an hour:
Raise the rear on a stand.
Remove the rubber caps from the swingarm axle (pivot side) and slide a 24" 1/2" dia steel rod through the axle.
Use two jackstands to support the bike at the rod and remove the rearstand.
Now pop the rubber cap on the swingarm and loosen the bottom shock heim joint. Tape the allen/socket/extension together so you do not lose anything inside the swingarm. You may need to loosen the top of the shock too.
Now swing the arm the full arc and notice how loose/tight your chain is. Adjust so it is free at the max extension.
Put everything back, then note the measurement on the sidestand for future reference.
I'll definately be giving this a try next weekend.
And to clarify... I'm at 20-25mm with me on the bike. Thats less than 1-inch. Unladen, sure, closer to 2-2 1/2 inches, but that was just an estimate.
Also, while sitting on the bike, the swinarm is still at an upward angle, from the axel to the pivot. So theres still some suspention travel before it reaches is longest point. I seem to remember dad swapped out the ride height adjuster, but I'm not sure what exactly went in, from which bike, leangth etc. I just think and inch or less slack, knowing that there's still some travel I need to compensate for seems OK, at least until I can take the time to check with the shock and adjuster detached.
How many teeth on the two sprockets?
If you have 15/45 or 14/42 you have an exact multiple and you'll get harmonic noise no matter what you do. I had that problem on my ST2 for a while.
last time I heard/saw anything like this was when the front sprocket was installed backward
I know you said the rear sprocket and chain are laser aligned
but
the bike I saw this on was in to the shop several times for chain adjustment and they didn't catch it either
ther wasn't any odd wear until several thousand miles later
Quote from: ScottRNelson on April 27, 2010, 01:09:23 PM
How many teeth on the two sprockets?
OK, seriously, are you pulling my leg?
I'll bite: What would the combination of sprocket teath have to do with anything?
Just went to a 14T front. So it's now running 14/42.
Quote from: Mother on April 29, 2010, 02:20:39 AM
last time I heard/saw anything like this was when the front sprocket was installed backward...
Can't happen.
The Vortex 14T front I just installed was only tapped on one side for the bolts on the sprocket fixing plate.
Quote from: msh441 on April 30, 2010, 02:50:11 PM
Just went to a 14T front. So it's now running 14/42.
If the number of teeth on the rear sprocket is an even multiple of the number of teeth on the front, which yours now is, and which mine was, you'll get a harmonic vibration. The two will be in resonance with each other and make annoying sounds that you don't get with a non-multiple. That's one reason why I went with 15/44 rather than 15/45 when I put new sprockets on my ST2.
I didn't believe it either when someone else mentioned it, but I paid attention to the differences in number of teeth on the sprocket and could tell that it was happening.
And there's nothing you can do to make it go away short of changing to sprockets that are not even multiples.
Quote from: msh441 on April 30, 2010, 02:50:11 PM
~~~snip~~~
Can't happen.
The Vortex 14T front I just installed was only tapped on one side for the bolts on the sprocket fixing plate.
Every front sprocket for a Ducati that I've seen can be installed 2 ways.
"Flat side" out
"hub side" out
Which way is yours installed?
Quote from: Speeddog on April 30, 2010, 03:19:34 PM
Every front sprocket for a Ducati that I've seen can be installed 2 ways.
"Flat side" out
"hub side" out
Which way is yours installed?
99.9% sure it would be considered "hub side out"... with the flat side inward, toward the case.
Quote from: msh441 on April 30, 2010, 08:08:42 PM
99.9% sure it would be considered "hub side out"... with the flat side inward, toward the case.
OK, that's good.