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Thread: Winter Layup - 1995 Ducati 900 Supersport

  1. #61
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lifted the engine again, got the adaptor to the car engine stand off, notched it so that I can access the swingarm bearings.

    Also cleaned the cylinder base gasket rings up (CRC and 800-grit paper) for re-use.
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  2. #62
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lower Hutt
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    Front subframe and swingarm off at powder coater's - Powder Coating Services, 51 Port Road. The boss runs a VFR800, took a minute from his (frantic) day to have a chat with me... good stuff.

    Had my 8 - 12 mm bore transfer gauge arrive tonight, so I got stuck in. Engine measurement time.

    The transfer gauge (in photo, by micrometer) takes an internal diameter, then you pull the gauge out and put the micrometer onto it. $40 out of Trade Tools. Way cheaper than a specialist bore gauge, if not as convenient. It also can't be used in a reverse taper, since it can't be withdrawn while locked.

    Piston rings were measured as per factory manual procedure - insert into relevant cylinder at base of stroke, push it in square (I used the piston), then measure end gap with a feeler gauge. It's down a way because there's a bit of an insertion taper, you want the ring sitting in the parallel part of the bore.

    Anyway - results:

    All compression rings are at their service limits.

    Both oil control rings are (just) beyond their wear limits.

    Both intake valve guide clearances are at or beyond their service limits.

    Both exhaust valve guide clearances are at or beyond their wear limits.

    So that's pretty clear. New rings, new guides. Maybe new valves. I'll have to check what the valve stem diameters are supposed to be brand new and compare that to what I've got. There are still a few measurements to do - gudgeon pin and piston skirt clearances - but I'll need more gear for that.

    The main thing I'm taking from this night's work is that going on feel and guesswork is fine but measuring is knowing... I wouldn't have picked how bad the oil control rings were getting to be.
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  3. #63
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lower Hutt
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    More measurements, this time the pistons and cylinders. One of the big decisions was to re-ring or go for high-comp pistons.

    So -

    Ring end float within service limits

    Gudgeon pin to piston - apparently on wear limit, but it's a very close tolerance, very easy to exaggerate measurement with the gear I'm using.

    Piston skirt to cylinder wall within service limits - same issue as above. The transfer gauges work well with small diameters but get tricky with the bigger stuff. It's easy to go narrower than the full diameter, giving a low result, or angle the thing and get a high result. It took several tries to get results I was happy with.

    Cylinder taper and ovality below limits of measurement, decision made that they're both OK.

    I measured valve seats as well. The test is the width of the contact ring, it's supposed to be between 1mm to 1.5mm wide. The horizontal head was on that limit, the vertical limit came in at 1.8mm exhaust and 1.7mm inlet. The exhaust valve seat shows visible recession, with a lip forming at the outer edge, over the valve head.

    So pistons and cylinders are good to re-ring and go, but the heads need new valve seats.
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  4. #64
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lower Hutt
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    Gudgeon pins and small end bushings checked out as being within service limits as well.

    Then I got onto the clutch... I'd been on tour with a mate and had a momentary problem with the clutch. It started slipping on half-throttle or more. Pulling over, shutting down, and working the clutch a few times sorted it out for the rest of the trip. Worth checking while I've got the motor in bits, and anyway it has to come off if I'm pulling the cover.

    So here's the famous dry Ducati clutch being pulled to bits. The sequence is:

    - Cover off
    - 6 springs off
    - Pressure plate off (the throw rod might come with it, if it's jammed in - it'll pull clear)
    - Lock the clutch up and undo the 32mm nut from the hub
    - Remove locking tool
    - steels and friction plates pulled and stacked. I chose to number them (not really necessary), a magnetic pickup tool is very helpful for this.
    - Locking tool back on, undo 8 x M8 bolts
    - clutch basket off

    It sounds like a big drama but really takes about an hour.
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  5. #65
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lower Hutt
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    Having a closer look at the clutch now that it's on the bench.

    The clutch cover is gouged (a little) on its inside. This cover must have had a gasket at some point, now it's running close to the spring cups. Not good.

    The O-rings on the pushrod are well and truly shot. There was engine oil inside the hub, thankfully it hadn't made it to the plates... not sure where it's coming from, possibly a loose gasket, or a failing shaft seal. Either that's been happening with the bike running, or oil has been flowing with the motor turned on the stand.

    The anodisation on the cheapo no-brand hub has gone notchy. Really notchy. The OEM Ducati hub isn't finished in any way, this kind of thing happening might be why. The steels have to be free to slide back and forth on the hub - if they don't then the clutch won't release properly. Not a problem when rolling but it can make neutral difficult to find, especially with a short-throw clutch slave like one of the Oberons.

    The cheap hub is also badly dimensioned. There's a spigot at center which is there to locate the petal washer, but it's just a shade too tall. The petal washer at center isn't gripped by the main nut properly, it's been rattling back and forth instead and is notching its way into the spring posts.

    The basket is notched too. This is an old basket which I'd filed out previously... it's well beyond the usual flange clearance to the friction plates, but works. Sort of. A closer look showed a mix of friction plate dust and rust forming a layer on the inside of the basket fingers. With a loose flange clearance, sometimes the friction plates can run on these surfaces. If they jam up on dust and rust, the whole stack could go angled... slipping clutch follows. Maybe.
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    Last edited by OddDuck; 21st May 2016 at 18:24. Reason: Forgot about the cover

  6. #66
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Here's the engine oil pump cover coming off. Note the oil and dust spray behind the clutch basket, it wasn't like this the last time I got into the clutch. Looks like one or both of the seals have gone.

    There's an O-ring (partially squashed and set) just inside this engine cover, not sure of its position in the oil circuit yet. The pump itself had a couple more. Someone's been in here before, there was a recoil used in one of the pump's mounting threads.

    The oil pump comes off easily with three screws, loosen the oil pump cover screws first though. The oil pump itself is checked with a feeler gauge and straightedge.

    Clearance between rotor gear tips and housing - very good

    End play clearance - outside spec

    Rotor tooth to tooth clearance - well outside spec

    Interesting, I haven't been having any issues with low oil pressure warnings.
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  7. #67
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    19th January 2006 - 19:13
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    Applaud your work mate good on you,should get off my arse and give my old S some lovin to be honest.
    Be the person your dog thinks you are...

  8. #68
    Join Date
    14th July 2006 - 21:39
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    2015, Ducati Streetfighter
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    Christchurch
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    Quote Originally Posted by 98tls View Post
    Applaud your work mate good on you,should get off my arse and give my old S some lovin to be honest.
    Agree. I've had a tail tidy project in various stages in my garage all year. Given the above work I should pull finger and fit the bloody thing tomorrow.

  9. #69
    Join Date
    20th January 2008 - 17:29
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    1972 Norton Commando
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    Auckland NZ's Epicentre
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    Your getting close to splitting the cases.

    I was talking to a mate who is building an F1 replica ( replica) and the cracking of the frames came up. He said the frames are not made of anything special and the cracking is common. He went on to say that fitting an internal sleeve was the way to go but that probably means more work I'd say.
    He said there is a guy called Muzza who is a good guy to deal with in ChCh as he has got parts and info from him. ( can't be too many Muzza's who work on Ducatis )
    DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.

  10. #70
    Join Date
    7th March 2006 - 21:17
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    Kawasaki Vulcan
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    New plymouth
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    Winter Layup - 1995 Ducati 900 Supersport

    Brilliant thread OD, great work.


    Sent from my iPhone using Tapatalk

  11. #71
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lower Hutt
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    98TLS, AllanB, Voltaire, Ruaphu - thanks guys. Appreciate your support.

    Voltaire - thanks for the idea about the frame. Not quite sure what you mean - do I cut a length of tubing out of the frame completely? What's involved?

  12. #72
    Join Date
    28th January 2015 - 16:17
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    2000 Ducati ST2
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    And carrying on... working again today.

    I started with the clutch, doing things like measuring the plates and steels (all OK), the plate tang clearance (miles out, since I'd filed the basket fingers linear again), then I got sidetracked. First, there's the star washer, which has been rattling around and cutting its way into the spring posts. Second, the clutch has been either a pig to get into neutral, or if neutral's sweet, it slips under power... it got me thinking.

    The star washer was simple - shave a couple of components down in the right places via 180-grit wet'n'dry, CRC, and a flat block. Crush is then restored to where it should be.

    The clutch, though. I had a look at the basket, the hub, and the steels, and I reckon Ducati's made a bit of a design mistake. The steels are punch-pressed from sheet metal and then deburred in a vibratory tub. They are not chamfered.

    This means that after the steels have very slightly cut their way into the hub (which is much softer), there's an edge which can easily bind up during the linear travel that the clutch plate assembly has to do while releasing or engaging. It's made worse by the anodised hub, since the anodised skin isn't wearing smoothly down to parent metal. It's coming off in sharp-edged flakes instead. Even it this wasn't happening, the steels having no taper whatever means that they can't climb any sort of angle without digging in.

    Taper (chamfer) needed: I spent three hours going over them with a needle file. I was careful with vise compression and not bending the steels.

    This did improve things, trying plates on the hub while applying torque and comparing to non-filed originals. Much less notchy. The chamfer has to be big enough to overcome wear features but no more - say about 0.05 mm high by 0.1 wide, or something like that. It has to be on every face of the steel's internal spline.
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  13. #73
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    28th January 2015 - 16:17
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    2000 Ducati ST2
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    Lower Hutt
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    Taking the alternator cover off.

    First, you don't have to have the special tool. It can be done with a pillar bearing puller and a couple of long M6 bolts with mudguard washers. The permanent magnet for the alternator is quite strong and a controlled motion is needed. It takes about twenty minutes to get the cover off.

    A few notes... the gasket turned out to have a bend and a split. This is from fitting it with the motor in the frame, about six months ago when I had to replace the stator. Next time I fit gaskets, they're going on horizontal, so they sit where they should. 100% my fault, and a reminder for this job: check everything. I would never have expected to see a gasket bend in situ and tear like this.

    The stator windings and wiring is fine, the seal on the case cover isn't. It leaks like hell. There was oil everywhere when I stripped the bike down, I'll have to revise what I've done here... and the plain PVC sheath on the wiring (as supplied by the aftermarket stator manufacturer) was simply not up to the job. It's gone hard. I'll have to cut it from the wiring before I try to remove the stator.

    Last time I'd been in to this cover, I'd found the reason for the hesitation when using the starter motor (it really struggled). It was loose on its three mounting screws. The path for the current uses this mounting and depends on having a broad contact area. If you're having similar trouble getting the engine to turn over, try grabbing the starter and making sure it's tight to the engine.
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  14. #74
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    28th January 2015 - 16:17
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    Tonight's effort: have a go at taking the cylinder studs off.

    CRC 5.56 applied liberally, then I got stuck in with a poor man's stud extractor. It's just a pair of nuts tightened against each other, with either a flat or spring washer between them.

    I was careful with tightening them up: that was done with the spanners as close to each other as possible. Don't want to load the stud up sideways, not when it's this long - too easy to snap it off at the root. Unscrewing is then with the handle on top and using both hands, one each side with the sliding handle centered. If that's not enough, the spanner and handle at 180 degrees and equal force up and down on each side. Pure torque, no bending.

    The studs themselves actually did come out reasonably easily. No Loctite present, surprisingly. I did a lot of working back and forth during unscrewing, using CRC and making sure that the threads weren't binding up. It turned out that zinc plated nuts didn't grip chromed studs as well as plain stainless steel nuts did, and then in turn high-tensile steel nuts were better on the black finished studs. Also it turned out that this technique is limited to about 30 Nm. I couldn't quite get the very last stud.
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  15. #75
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    24th December 2012 - 21:49
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    Quote Originally Posted by OddDuck View Post
    Tonight's effort: have a go at taking the cylinder studs off.

    CRC 5.56 applied liberally, then I got stuck in with a poor man's stud extractor. It's just a pair of nuts tightened against each other, with either a flat or spring washer between them.

    I was careful with tightening them up: that was done with the spanners as close to each other as possible. Don't want to load the stud up sideways, not when it's this long - too easy to snap it off at the root. Unscrewing is then with the handle on top and using both hands, one each side with the sliding handle centered. If that's not enough, the spanner and handle at 180 degrees and equal force up and down on each side. Pure torque, no bending.

    The studs themselves actually did come out reasonably easily. No Loctite present, surprisingly. I did a lot of working back and forth during unscrewing, using CRC and making sure that the threads weren't binding up. It turned out that zinc plated nuts didn't grip chromed studs as well as plain stainless steel nuts did, and then in turn high-tensile steel nuts were better on the black finished studs. Also it turned out that this technique is limited to about 30 Nm. I couldn't quite get the very last stud.
    stand it up so the CRC has a chance to seep down between the threads
    maybe warm up the area along the side and let it cool down then apply CRC and try the next day.

    spring washers of today are crap

    great to watch your effort. If I was doing it they would have been broken off before I had removed the rest

    READ AND UDESTAND

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