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Discussion Starter #1
I'm around 1000 miles into a 2000 mile trip and I have a couple of worrisome vibrations, possibly related, in my '93 900ss that I cannot figure out.

(1) at 4000 rpm in 5th, there is a modulated ~60 hz vibration that can be felt most strongly in the footpegs but through the whole bike. In 4th the frequency goes up, in 6th it is not very noticeable. It seems to be getting worse. You can accelerate through this vibration to where it is not noticeable.

(2) when letting off the throttle, or with a barely cracked throttle, in any gear, there is a 'bag of marbles' type random knocking that can be felt through the footpegs - feels like something is loose an banging around. Under hard deceleration, this ends up as a continuous buzz. Hitting the throttle smooths things out immediately, as does pulling the clutch in.

Here's what I've done so far to troubleshoot:

- pulling in the clutch at speed makes either trouble disappear

- under hard load everything is smooth. I cranked it up to 110 for a bit and had no problems.

- lightly pushing in the clutch, just putting a bit of pressure on it, makes (2) go away

- thinking a loose clutch basket or hub to be the culprit, I disassembled the clutch completely this morning at a buddy's place in KC, MO and found no evidence of trouble. The only thing I noted was that I can wiggle the basket a tiny bit once it is firmly fixed to the clutch gear. At first I thought I had a loose basket, but this was not the case. Maybe the bearings are going south? Should I pull the cover there and check the cover bearing and or the one behind the transmission gear that the basket attaches to?

- checked Engine mounting bolts - no trouble there.

It sure seems like the trouble is in the transmission at this point, but should I pull the flywheel cover to check the alternator an flywheel?
 

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real help

how about a trip to reno's powersports of KC? sounds like you're close by. if you've got serious but undiagnosed trouble, a real ducati tech could save your butt.
 

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I would pull your alt.cover and check your alt. nut, if that goes south then your alt & flywheel will eat your stator! :eek:
 

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This is not likely your problem but pop the covers and have a look at the belts and idler pulleys. Had one get crunchy and give me some vibration. Also had a cam pulley nut back off (assembly error in this case) and it also caused vibration under constant speed.
 

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Discussion Starter #6
Check your chain and sprockets, they can make some very straing vibrations and noises.
I'm another 700 miles in and bike is running fine, albeit with these two minor issues. Neither is getting worse as of yet. The chain was a bit loose and shows signs of uneven wear at 5K - maybe I set it up a bit too tight and now I'm paying the price? I tightened it a bit but it didn't seem to make any difference. I decided to risk not pulling the alternator cover as I didn't have a good workspace to do it at my folks' place.
 

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Discussion Starter #7
This is not likely your problem but pop the covers and have a look at the belts and idler pulleys. Had one get crunchy and give me some vibration. Also had a cam pulley nut back off (assembly error in this case) and it also caused vibration under constant speed.
I had the belts off just before leaving on this trip to replace the belt drive oil seal the the idlers seemed OK. I'm doing the belts soon after I get back to Austin so I'll pay close attention to this during that job.
 
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