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1993 900 SS - issues and niggles

33374 Views 357 Replies 28 Participants Last post by  Helgeduc
Late last year I bought a 1993 Ducati 900 SS with 52000km from a German, private seller. He was the second owner, with the bike having been registered to the first owner for 24 years, The seller had ridden the bike for a mere 2000km. She was in pretty good condition visually: clean, mostly stock with all original parts available, as well as some carbon fibre aftermarket parts (front fender, rear hugger, sprocket cover). I like originality in a bike - at least if I do not wish to modify - and for this bike originality was higher on the list of "must haves" than lower miles, etc. She also came with additional parts (gaskets, spark plugs, carbs) as well as manuals and specific tools (head bolt wrench, clutch basket holder,...).

The seller claimed she was "dry", with the exception of a little oil weep at the rear cylinder. I checked for frame cracks or indications that the bike had been down harder than just a tip over. Nothing. According to the seller, he had to replace the swing arm. The well known cracks. He also mentioned that he had broken off the turn signal control stalk and replaced the left side control unit. He also had exchanged the footpeg hangers with the black colored ones from a later model (this is one of only two items, where the original part was not included in the deal).

When we tried to start the bike for a test ride, the brandnew Li-ion battery was dead. Odd, but hey... We fitted a standard battery and I tried to take off. And stalled the bike - pretty rough clutch, but these bikes are known for them, after all!? We got her running and I took off. And did not get too far. After a couple of kms she started to hickup and eventually died on me. One thing I noticed was how noisy the bike was: the stock cans had at the time of the initial purchase been replaced by open BOS exhausts - and I still wonder how the bike EVER made it through the German TUEV technical control...

Based on how the bike had behaved before it died on me, I suspected having run out of gas and called the seller. When he arrived, it became clear that the fuel punp was not running, which could be traced to a blown fuse. Replacing the fuse did not remedy matters, so we suspected a dead fuel pump, loaded her up and I used the issue as a bargaining chip to reduce the price some.

I brought her home and started to go through her. I'll use this post to describe what I found and learned - I have found similar posts (and the many helpful replies I received when I asked for help) very helpful. I hope this one will achieve the same.
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I used the high strength Loctite on purpose. I am willing to minimize the risk of unintentionally uninstalling a head stud via a stuck head nut, knowing that future head stud extraction may be more challenging. I suspect (hope?!) that I will not have to uninstall the head studs anytime soon.
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Folks, I will put also new shoes on the lady and am considering to go from my current Michelin Pilot Power (with which I am happy on the road in dry conditions) to something more sticky.
I am unlikely to use the bike on the track, but won‘t mind additional grip. Since I am not riding that much (and the bike does not have THAT much power), I am willing to pay extra for more grip in corners but less tire life time. I could also imagine using a tire with significantly softer rubber the further you move away from centerline.
I would like to keep the 170 in the rear as in my experience putting a wider tire on a (too) narrow rim is most of the time not a great idea.
Any suggestions?
I’ve opted for Metzler M9RR’s for my ‘95 900SS build. From memory they were only available in a 180/55 though.

From what I read a 5.5inch wheel should have a 180 tyre on it though (provided you’ve got the wider SS wheel).
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How do you do the strike through thing?
How do you do the strike through thing?
The struck through S (fifth symbol from the left) in the bar below the input field.
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Depainted my „new“ oil cooler. 2k paint should arrive early next week. A lot of work to straighten the cooling fins :-(
I‘ll pay A LOT of attention not to bugger this one up last minute as well…
Grille Rectangle Automotive exterior Gas Composite material

Still waiting for the heads :-(
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Nice work!
I “mock“ installed pistons and cylinders today (left o-rings, etc off for now). Intent is to install the heads when they arrive, measure and set squish, then do final assembly.
When I tried last night I realized that if I install the piston on the rod first, then use the piston ring compressor to slip the cylinder over it, I have a really hard time getting the compressor off as there is not much room to wiggle (the head studs are in the way). After some more thought I figured out a way that works ok for me: I install the gap of the compressor around one stud, slip on the cylinder, then bend one side of the compressor to the outside of the stud, then slowly turn the compressor until it unwinds itself from the inside of the studs to the outside. At that time it can be easily removed.
Probably completely standard procedure but it took me some time to think it through (I actually slipped the first piston into its cylinder on the bench. But having seen how hard a time Andy of Andy‘s MC Obsessions had to get the piston pin circlip in place I‘d rather get the piston on the rod first…).

Question to the pros here: I took out only one piston pin circlip and left the other in situ. I will replace the one that I removed. But do I also have to replace the one that remained on the piston?
Thanks!!
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I put the piston in the barrel before assembly just because it's less time consuming than compressing the rings as I was concerned with the 3bond setting up. I did see that Andy had some problems with the circlip, but I didn't have any problems. I simply inserted the open end in first and then just pushed it in. I did have to be careful that I didn't drop the circlip into the engine which would've been problematic.
Were your new circlips the same shape as the old ones? My new ones are missing the little bend at the end…
I went with the high compression kit from JE Pistons, and the circlips were the same as the OEM ones I pulled out, but neither one of them had a bend at the end. Maybe post a pic of them.
I went with the high compression kit from JE Pistons, and the circlips were the same as the OEM ones I pulled out, but neither one of them had a bend at the end. Maybe post a pic of them.
Her are the old and the new circlip. Note the bend on the old circlip (left). It goes in a groove on the piston.
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All: any comment as to whether it is ok to leave the untouched old circlip in place without replacing it? (See my earlier question)
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Cylinder heads are back. Exhaust valve guides needed some work and a few new bearings - all at very reasonable cost :)
I hope to get to look at squish this WE.
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Awesome, the shiny, cool, new head nuts I bought do not fit the home made torque tool I inherited from the PO. So I spent more than an hour yesterday to decrud the old nuts…
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Do you not know anyone that can weld? Might be an idea to get another tool or some other arrangement.. Provided the torque wrench is at 90° you're fine.
Do you not know anyone that can weld? Might be an idea to get another tool or some other arrangement.. Provided the torque wrench is at 90° you're fine.
Maybe later. The weather is starting to be really nice - and I want to get back on the road. So I‘ll use the old nuts for now.
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So I measured squish using modeler‘s clay.
Motor vehicle Automotive tire Automotive design Wheel Tire

Automotive tire Automotive wheel system Rim Machine Auto part

And lo and behold I get about 1.1mm on both using the old gasket / spacer. Very close to what ducvet recommended. I am happy with that.

Now I‘ll reread the manual to make sure I do not forget any O-ring or such and hopefully button the engine up next week.
Progress.
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And I managed to drop one of the piston pin circlips into the engine. (No, I won‘t need the rug in the bore… Jeez, when do I learn not to take shortcuts???).
An extendable magnet is your friend!
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Out of curiosity: does anybody know why only the vertical cylinder has an o-ring between cylinder and case at the oil line, but not the horizontal cylinder?
The engine is looking spectacular!
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Very nice progress, I’ve been enjoying watching your progress.

Years ago I used modeling clay to measure valve to piston clearance on my old GS750E, it worked like a charm.

1.1mm is just over .040 inches which seems to be target quench in the Chevy V-8 arena. I had a 355ci small block professionally built for my 69 vette, the builder used 0 deck height and a .040 head gasket for a nice tight chamber. Little monster made 440hp/450tq
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