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Discussion Starter #1
OK Ducati techs here is a chance to show your stuff. Out riding my 93 900SL the other day when I heard what sounded like a car spinning the tires in the distance. Not so, it was my bike. It only occurs when the engine is fully warmed up. It sounds somewhat like a loose power steering or fan belt on a car. It happens in gear or out of gear and with the clutch in or out. I have previously replaced the bearing in the clutch pressure plate as I could hear a slight squeek when I spun the piece on the end of the clutch pushrod. Put a bit of lube on the pushrod ends and o rings in case a dragging pressure plate bearing was causing the pushrod to spin. No change. Leads me to believe that it is not transmission related. I pulled off the fairing lowers and belt guards to observe the belt tensioner rollers. They feel fine and seem to be spinning in sync with the belt motion. These are new belts and they are tensioned properly. All ball or roller bearings inside the cases and I don't see how a cage failure could cause this sort of noise. Also no metal particles in the filter screen. It really sounds like squeeling rubber. Any chance one of the belt tensioner rollers, when hot, is exhibiting enough drag to make the belt squeel? Oh yea, the sound is intermittent. While idling fully warmed up it might squeel for only 2 seconds in a minute or off and on for 20 seconds in a minute. I have a 95 900SS SP also and the belt roller resistance to rotation feels the same on both bikes. Other than this noise the engine runs perfectly. Any ideas? Thank you in advance.
 

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gregsky said:
Any chance one of the belt tensioner rollers, when hot, is exhibiting enough drag to make the belt squeel?
exactly what I was thinking!
 

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It might be worthwhile pulling the clutch plates out of the basket and generally just cleaning in there. Check the retaining springs are torqued correctly etc etc. Just a thought.
 

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There are a couple of bearings on the clutch pushrod that sometimes get rusty which will make them squeal like a stuck pig. They're not sealed and they get no lube.
 

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if the sound is coming from the right side of the engine...

1. belt tension rollers may need lubing or replacing as someone previously stated.

2. on most carbed bikes, on the vertical cylinder, there is a black rubber/plastic cover that fits between the head/cylinder and the top toothed pulley. sometimes, the belt can rub on the rubber/plastic cover (ie: engine heats up, expands, and pushes the rubber/plastic cover against the toothed pulley/belt).

there are some other things but i'd check those out first.
 

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Discussion Starter #6
Yeloduke Which bearings?

yeloduke said:
There are a couple of bearings on the clutch pushrod that sometimes get rusty which will make them squeal like a stuck pig. They're not sealed and they get no lube.
Are you speaking of #s 18 and 20 in the illustration? These bearings in the primary driven gear would get lube from the interior of the gearbox. Even so I suppose they could be junk. I have pulled the plates and center hub off the clutch shaft and felt for play in the shaft and primary driven gear bearings. Maybe it is time to pull the cover and give these bearings a closer look. Thanks.
 

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Discussion Starter #7
edwyun said:
if the sound is coming from the right side of the engine...

1. belt tension rollers may need lubing or replacing as someone previously stated.

2. on most carbed bikes, on the vertical cylinder, there is a black rubber/plastic cover that fits between the head/cylinder and the top toothed pulley. sometimes, the belt can rub on the rubber/plastic cover (ie: engine heats up, expands, and pushes the rubber/plastic cover against the toothed pulley/belt).

there are some other things but i'd check those out first.
I have tried the screwdriver to the ear trick and I can't tell where this sound originates. I too wondered about interference between the vert. cyl. rubber shroud and the belts but there is plenty of clearance. I may next swap the tensioner rollers off of my 95 and see what happens. Anything else you can think of?
 

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Screechy noise...

I had a similar noise as you describe... tried the screwdriver-to-the-ear trick -inspected everything, and found nothing. So, I took the whole motor apart (I was about to do hi-pop JE pistons anyway) and in the end found the springie-thing that holds the rollers for the starter sprag clutch had gone limp and was allowing the rollers to drag at some RPM's, sporatically, but tended to happen more when the bike was hot. It took me a while to figure it out... but a new sprag fixed it and it has not been back in over 12K miles. I had heard the early SS's around our vintage had problems with them....

Good luck,
Rich D.
 

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Discussion Starter #9
Thanks Rich

This might be the source. I think that if the noise has anything to do with the cam belt rollers that the covers would resonate like a speaker cone and it would be easy to isolate that the noise was coming from inside. When I was trying to isolate the location it seemed like the sound was more intense when touching the screwdriver tip to the left side of the engine cases between the two cylinders. This would be in the right neighborhood for what you are talking about.
 

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Discussion Starter #10
Pulled the sprag clutch out and it looks great. No slack in the spring. Perhaps it was replaced in the recent past. Very minor ripples on the engagemant surface of the starter driven gear from sprag engagement.
Anyone have any other ideas? I still have not tried the tensioner roller swap.
That is next I guess.
 
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