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Discussion Starter · #1 ·
Hello all,

I'm back in the Ducati fold again after writing off my 888 last year. Based in Nottingham UK and joined this forum as there seems to be a lot of excellent ST knowledge here! A few months back I bought a recently neglected (and so cheap) 2002 BBG. So far its been pretty much an exercise in frustration getting it running right! Jobs done so far;

Broken mirror spring mount. Several fairing tabs repaired. Leaking fuel tank traced to a failed seam which is now fixed with tank sealant. Oil, belts, fuel and oil filters changed as bike not serviced properly for 5 years (though only 3000 miles previously). New rear pads (one had no material left). Intermittent weird dash coupled with starting failure traced to failing ignition relay. Wobbly dash traced to failed anti-vibration mount. Rear suspension ride height adjuster was in its original position so was taken off, loosened off and rear raised so the tyre is just off the ground on centre stands. I am aiming to strip and rebuild the suspension over the winter at the same time as I do a valve etc service.

I love the riding position and seems just on the right side of sporty to me. Even better is a steering lock that actually allows you to turn sharp corners. Handling wise it feels great though the front feels a little light after the 888. The extra power of the 996 engine does not seem too obvious after the 888 though picks the front end up easily pulling away in first. It generally feels a little bit too civilised to me after the 888 (which is maybe why it doesn’t feel much faster) so I think I need to liberate some intake and exhaust noise :D I am still left with 3 concerns that are proving harder to sort;

1. Brakes. I have the pulsing brake lever at low speed and brake shudder at medium and faster speeds. I checked the nearly new Brembo discs for run-out on my lathe and they both seem OK though obviously difficult to check accurately with semi-floating carriers. Disc thickness checked with micrometer at 3.90-3.95mm for both discs over the whole surface. Freeing the bobbins didn't help. Cleaning discs with angle grinder (wire attachment) didn't help. Converting discs to fully floating (by cutting out the star washers) didn't help either. Brake pistons all free and cleaned. Head bearings, wheel bearings etc all OK. I've seen all the threads on this but don't understand how I can have a pulsing front lever if the thickness is constant and the discs are floating. I’m tempted to try a pair of the cheap Chinese discs just to see but am open to suggestions of what else to try.

2. Tachometer. Initially OK but went loopy after the last run (probably not helped by the failed dash mount). Currently reading 4000 rpm at tickover and barely moves when revved. Tightening the 3 brass screws at the back made no difference so I cut it open. There were no obvious problems with the circuit board so I remade all the solder connections in case of a dry joint and put it back together to find no difference. I have checked the voltage feed and earth as OK. Before I try and track down another tachometer can someone confirm what voltage I should get at the feed from the ECU just in case I have an ECU problem? Currently 11.5V DC with ignition on (ie about 1 V less that the 12V feed) and drops to ~2.5V (both AC and DC) when running. The voltage doesn’t appear to change when the engine is revved. I don’t have an oscilloscope to check the wave form but may be able to borrow one.

3. Vibration. The engine feels slightly smoother pottering around town below 4k rpm than the 888 which is nice. However, at higher rpm it shakes/vibrates when the throttle is opened wide which the 888 didn't do to (except at really high rpm). Cruising on a low to moderate throttle is fine but giving it a handfull eg at ~6k range brings on the vibes. Mirrors, dash and rev counter all vibrate and the last ride was causing me really bad white finger (I do suffer some times). Thus, I am wondering if the 996 engine is just generally more viby or if something is loose/not right somewhere (I've already checked pretty much all bolts including the main engine mounts). The engine sounds super smooth with no abnormal noises and the oil and screen were clear of anything nasty.

Any suggestions much appreciated!! Thanks, Keith
 

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Sounds like the previous owner didn't keep it up all that well. My tach started getting weird so I disconnected all the terminals, clean everything up well and reconnected it with dielectric grease. It's good to do that on all of your connections really.

I never rode a 888 but maybe the gearing accounts for the difference. And/or the rough engine means that a tune up is in order. A smoother engine around town than the open road is the opposite of my experience.

I am more concerned with gas mileage than lifting the front wheel off the ground myself so figure out what you're willing to sacrifice before you get too carried away with performance doodads.
 

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Life is too short to worry !
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From my recollection the discs should be 5mm with a min of 4.5 mm so they probably need replacing anyway , pulsing , or not.

Does the engine run rough when revved high in a low gear ?
It could be wheel imbalance occuring at higher speeds.
Otherwise it probably just needs a good service TPS/Throttle balance to sort , it should be smooth...
 

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I have a vibration that manifests itself at around 4000rpm and goes away once I get to 5000rpm. Never noticed the mirrors and dash vibrating that bad and figure I just need a throttle body balance as the bike goes real well otherwise.

Yes the discs should be 5mm like Gearbox states.. Once I converted to full floating buttons the disc let go and I could measure the run out easily whereas before it was hard to measure. The pulse has almost vanished though.

Something else I have just noticed is the tach on mine is not reading below 1000rpm. It just jumps from 0 to 1000 intermittently until the bike is warm then seems to settle down. Other than that its fine.

How many k's on the bike? The tech reckons the balance on the TB's is not needed every 10k service so I missed the last one and I am only 2000km's past that and feel its needed so would definately look at getting that done if I was you.
 

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Hello all,

I'm back in the Ducati fold again after writing off my 888 last year.
Hi Keith and welcome to the forum.

It's very sad to hear of a very lovely and very rare 888 being written off. That would be my ultimate Ducati.
A few months back I bought a recently neglected (and so cheap) 2002 BBG.
Forgive my ignorance, but what's a BBG ?
 

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when I bought my bike the tach was dead. the dealer supplied me with a new one, provided I install it myself.
 

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Discussion Starter · #8 ·
From my recollection the discs should be 5mm with a min of 4.5 mm so they probably need replacing anyway , pulsing , or not.

Does the engine run rough when revved high in a low gear ?
It could be wheel imbalance occuring at higher speeds.
Otherwise it probably just needs a good service TPS/Throttle balance to sort , it should be smooth...
The discs are pretty new but are 4.0 mm discs rather than the correct 5.0 mm items. I'm assuming this is not ideal but I guess OK as that is what the earlier bikes ran.

Its not wheel balance as its smooth on part throttle but gets rough as I wind the throttle on. Thanks for confirming that it should run smooth. Hopefully a throttle balance etc will sort it. The plan is to strip out the suspension etc over the winter so I'll do the valves etc then.

Keith
 

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Discussion Starter · #9 ·
Hi Keith and welcome to the forum.

It's very sad to hear of a very lovely and very rare 888 being written off. That would be my ultimate Ducati.Forgive my ignorance, but what's a BBG ?
The 888 is still alive as it wasn't too bad. I bought it back from the insurance company and sold it to a mate. Its now back to being immaculate again. The 888s are lovely at 70 mph plus and for trackdays but I am just getting too old for the riding position. My right leg used to cramp something chronic......

Keith
 

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Discussion Starter · #10 ·
Sounds like the previous owner didn't keep it up all that well. My tach started getting weird so I disconnected all the terminals, clean everything up well and reconnected it with dielectric grease. It's good to do that on all of your connections really.

I never rode a 888 but maybe the gearing accounts for the difference. And/or the rough engine means that a tune up is in order. A smoother engine around town than the open road is the opposite of my experience.
The previous owner shouldn't be allowed to own a Ducati. It was immaculate when he got it and had just had a full service at a specilaist. When I got it 3000 miles and 5 years later it was a much different story.....

I am hoping a tune up may help. Throttle balance seems possible from what you are all saying so I'll see if I can dig out the vacuum gauges. The ST4S is smooth around town only in comparison to my 888 which was a bit of an animal. Any more than a sniff of thottle below 4K will certainly bring on the shakes but thats standard fare for a Ducati as I understand it :D

Keith
 

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The discs are pretty new but are 4.0 mm discs rather than the correct 5.0 mm items. I'm assuming this is not ideal but I guess OK as that is what the earlier bikes ran.

Its not wheel balance as its smooth on part throttle but gets rough as I wind the throttle on. Thanks for confirming that it should run smooth. Hopefully a throttle balance etc will sort it. The plan is to strip out the suspension etc over the winter so I'll do the valves etc then.

Keith
My workshop manual for my 2002 gives 5 mm disc thickness , cant say I know about the previous thin ones but 4mm seesm very thin as a starting point ?

My 2005 bike runs happilly ndown to 2500 provided only part throttle , its so good I have not kept the PC3 installed on it that I had from my 2002 bike even though I had it custom mapped (The PC3 did not make a significant difference to this bike whereas the improvement on the 200e engine was plainly noticeable)
 

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My workshop manual for my 2002 gives 5 mm disc thickness , cant say I know about the previous thin ones but 4mm seesm very thin as a starting point ?
Perhaps he means a comparison to the ST2 when he says, "...but I guess OK as that is what the earlier bikes ran."

I say this as I just checked, and my ST2 manual lists 4.0mm as the thickness for new discs, with 3.6mm for the minimum thickness for serviceable discs.
 

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Discussion Starter · #13 ·
Yeah, I meant earlier Ducatis in general. My 888 had 4.0 mm discs as well on what seems to be the same calipers and that braked pretty good.

Keith
 

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Bad brake vibration upon actuation can come from someone in the past grabbing a disk with a greasy hand, not cleaning and then braking hard. The greasy area causes a glaze that is not slways readly apparent. Surface sanding the entire disk can usually repair this .

Bob
 

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Yeah, I meant earlier Ducatis in general. My 888 had 4.0 mm discs as well on what seems to be the same calipers and that braked pretty good.

Keith
Something new learned every day :)
 

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I have a vibration that manifests itself at around 4000rpm and goes away once I get to 5000rpm. Never noticed the mirrors and dash vibrating that bad and figure I just need a throttle body balance as the bike goes real well otherwise.

Yes the discs should be 5mm like Gearbox states.. Once I converted to full floating buttons the disc let go and I could measure the run out easily whereas before it was hard to measure. The pulse has almost vanished though.

Something else I have just noticed is the tach on mine is not reading below 1000rpm. It just jumps from 0 to 1000 intermittently until the bike is warm then seems to settle down. Other than that its fine.

How many k's on the bike? The tech reckons the balance on the TB's is not needed every 10k service so I missed the last one and I am only 2000km's past that and feel its needed so would definately look at getting that done if I was you.
That's the thing. Either the sync drifts over time or it is thrown off by shim swaps during the service. It'd say it is part of the valve service regardless.

Funny thing, I left the fuel filter change out of the service, going to a 10,000mi interval. I've gone way past that being lazy. I won't do that again.

BTW, 4mm disks here on my ST4. When I measured them many miles ago, when still on the original pads (in the brake pulses thread), they were still at 4mm.

Have a good one.
 

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Discussion Starter · #17 ·
Well, I seem to be making some progress! Rev counter fixed and working 100% again (see separate thread). The dash is also now bouncing around less now I fixed the one rubber mount that had fractured. Due to encouragement from you, I checked my TPS and it was high at 220 mv. Reset that and then found that the TB balance was a bit out as well. Got that spot on at 4000 rpm on the fast idle and then balanced it at tickover with air bleeds. The TPS was reading zero on DucatiDiag at tickover so I reset that that with the software and it now reads 2.5 degrees which sounds about right. The end result is a more robust tickover and a much smoother engine. I no longer have the shakes at full throttle. All I have now is a steadily increasing relatively slight vibration above about 8,000 rpm which is what my 888 used to do. Much happier!

I also stripped the discs off again. I sanded them lightly to an even buff colour and cleaned off the paint on the wheel flange in case that was throwing them out. Still no better :( I can clearly feel the lever pulsing at relatively low rpm so I dont think it can be anything else now! Thus, looks like I am going to bite the bullet on discs. So, do I go with the Chinese discs or try and track down a good second hand pair? I dont see why I should pay a vast premium for Brembo discs when they seem to warp so readily on this bike!

Thanks, Keith
 

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Mr Leakered
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Nice work. You should recheck the mid-RPMs after setting the air bleeds. It's an iterative process. That might be the source of your upper RPM shakes?

Motowheels just had a post for some used iron rotors that would fit an ST. They were pricey for used ones, but . . .

Have a good one.
 

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Discussion Starter · #19 ·
Yep, that makes sense. My 888 had the early style TB without air bleeds so there was less to play with. I still need to do valves/rocker check over the winter so balance will get done again after that! Certainly good enough for now though :)

There are a couple of sets of discs on auction on ebay in the UK so I'll keep a careful eye on those. I need to do something as braking is not nice. Light and heavy braking is not too bad but 'normal' braking is pretty unpleasant :eek:

Keith
 

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Before you splash out on new discs, have you cleaned the bobbins Keith ?

Stick the tail of a rat tail file into each bobbin and turn them as you spray with brake cleaner to get all the shit out. It might be as simple as that.
I put the file tail into a bit of rag first, so I don't score the inner face of the bobbins.
 
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