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I have just bought a low miles (10k) pampered ST4s and as I have owned Ducati’s since 1982 know that they like to spring mischief upon their owners and so I thought I would get your view on what to look at and pre-empt.
It’s a 2002 ST4s and has had 10x main dealer services, the last 30 miles before I bought it and included belts, check alternator nut, change all fluids, hoses, valves checked, plugs, rockers checked, clutch plate thickness is good, head race bearings good and compression is 190psi. It has new tyres, chain, sprockets (15/43), brake pads, battery, scottoiler and Quill carbon exhausts.
It starts instantly and runs very well and I am putting some miles on and tweaking suspension setup.
It is a Ducati so it will misbehave.
  • From those members who have put miles on ST4s’s what are the top 10 gremlins I will encounter and what is the best solution?
  • What is the best option for connecting to the ECU for analysis and fault diagnosis? I have a Buell and I can connect to the ECU via Bluetooth and hence to a phone app and easily diagnose issues – I assume something similar exists for an ST4s?
I appreciate your time in responding.
Paul, West Sussex, UK
 

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Main Harness connection inside the left front faring holds water and causes issues
Stator/RR connector corrodes and causes issues.
Google "JPDiag" and "ScanM5x"

Have Fun,
t_bare
 

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Trying to get the mid and upper fairing off is a total cluster fuck. Nearly impossible to do without breaking something.

Guess where the battery is?

:)


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First you take the mirrors off :ROFLMAO:... for everything.

t_bare
 

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Check to see if the starter wiring has been up graded yet.
Also see if the steering head bearings have been upgraded to tapered bearings.
 

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18 Years of ownership my list from experience not Internet folk law
  • Change gearing on bike by changing rear sprocket
  • Check all the loom as much as you can Pay attention to earthing and the main connector (back)
  • Change the seat to DP or Mk2 version
  • Change mirror bolts to thumb wheels for much better fairing removal
  • Replace worn sprockets with steel not aluminium
  • Move levers down closer to the ground by removing location pins and swivelling
  • Watch for flaking rockers (expensive labour costs)
  • Get a good quality battery and battery tender
  • Don’t fit the K&N crankcase breather
  • If you ride at all at night upgrade your lights, the stock unit is appalling
 

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Sounds pretty well sorted already. Only issues I can think of that haven't been mentioned are the relays potentially getting flaky after 20'ish years, and the temperature sensors being problematic.

Also if you're working on suspension and have an adjustable ride-height rod, you can assume it's probably seized and may need some coaxing (e.g. heat, penetrant, etc.) to free up.

Engine mount bolts were another wear item to check making sure they're torqued properly, not broken and no cracks in the case. Not sure which year, but they went from 10mm studs to 12mm, I believe the latter being less prone to failure.

A case-saver in front of the small sprocket was another recommendation --cheap insurance in the event of a flying chain.

Have fun with it!
 

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One you will not like and can be expensive...ECU failure. Noticeable when the bike suddenly wants to run on one cylinder.
Swingarm axle plates. Like butter and prone to bending out of shape. Plenty of aftermarket available. I have some desmo times billet pieces.
Snowflake front rotors can warp. Yes some can be frozen buttons but mine warped.
Rear tail side fairing middle mounts are fragile and crack very easily.

Not the top 10 but added for consideration :)
 

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You mentioned tweaking the suspension. The OEM rear suspension is set up for the mythical 160lb Italian rider. If you weigh more than that or will be doing a lot of two up riding, I suggest going to a heavier rear spring.

The OEM seats and headlights on the "old style" ST models, which includes your MY 02 ST4s, are not conducive for road trips. Some feel the same about the OEM windscreen. Upgrades to all of these have been discussed in the ST forum.

The 02-ST4s has a side stand safety switch and will not start or idle in neutral with the side stand down. The owner of my late 02-ST4s had installed a bypass switch, which later made the bike hard to start and sometimes ran down the battery. I had the switch removed and simply started the bike on its center stand.

Some have mentioned leaking gas caps. After filling up, close the gas cap and remove the key. Then press down on the gas cap with your thumb until you feel a click, which insures that the gas cap is securely sealed. Don't fill the tank above the bottom of the neck and don't put the bike on its side stand after filling up or gas will drain on to the engine. Guess how I know?

I had a European headlight switch installed on my old style ST models so I could turn off the headlights and warm up the bikes without draining the battery. If you go this route, make sure to get the headlight switch which allows the high and low beams to light at once. Some Euro headlight switches turn off the low beam when the high beam is engaged.
 

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Trying to get the mid and upper fairing off is a total cluster fuck. Nearly impossible to do without breaking something.

Guess where the battery is?

:)


Sent from my iPhone using Tapatalk Pro
There have been work-arounds for these "issues" that have been posted in the ST forum.

Paul Geller installed some type of knobs so the side view mirrors could be removed without removing the windscreen and dash. I believe others have removed a tab on a side fairing so that the battery can be accessed by only removing the middle fairing on the right side.

Members that have made these mods can elaborate further.
 

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A common issue not mentioned yet is the rear shockie top rocker bolts. Lift rear wheel while over pillion seat and see how much slop there is, then change the two smaller bolts if over about 1cm. This all comes off ride height, which should be set so rear wheel just misses the ground when on centrestand and new tyre.

Re elect, to be clear, the wires from the alternator to rectifier need a 'plug delete'. Fully solder the connection is the basic need, relocate the rectifier to behind the opening in bottom left fairing makes any maintenance simpler, but you have to make up a bracket for that. If the rect is original, replace it now. Don't wait for failure as you won't enjoy how it happens, which it will. There is a guy in the US that sells an on demand reg/ rect vs the total loss system most bikes use, it works great.
Another useful mod is to add a compact Nautilus air horn (and relay), which are cheap on eBay and scare the beejezus out of sleepy 4WD's that think a truck is about to hit them!
Personally, I love the fun factor a lightened flywheel brings to the seat-of-the-pants dyno, plus it becomes more flickable.
 

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Re that 02 ecu, not starting in neutral on sidestand, or in gear with clutch pulled in, peeved me off so much I managed to swap ecu (and immobiliser, which are ecu locked) out for '03 model which these issues don't exist. I forget now but '01 had similar sort of bs issue.
 

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I had an St4 in the late 90’ies and found an ST4s low mileage a few years back, first thing was I found it really hard to steer and found out the factory set the height to be able to carry full load on high speed, to cope with the high power.
Extending the rear suspension link, until the rear wheel is close to the ground when on center stand eases up the steering a lot, just be aware it is no more stable at high load with high speed.
The fairing is bad, seems brittle with lots of cracks, not sure how to fix...read about gluing using acetone but haven’t been able to source some yet. Just asking for acetone these days is complicated..
Fuel level indication unreliable, seems the connection under the tank is to blame, trying to figure out how to open the connector...
Using dielectric silicone grease in switches and connectors is said to be great ..
 

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I assume all of the in tank fuel lines were replaced,this typically is a problem area.Dunno how to pre-empt a fix,that particular year does seem to have an issue with the ecu,this causes a misfire .Yes regular frame bolt check tension, your year model will be 12 mm, you could even upgrade to TPO or Nichols. DONT get the gauges wet when washing (glad wrap them even) Regular oil changes.Theyre pretty reliable
 

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I assume all of the in tank fuel lines were replaced,this typically is a problem area.Dunno how to pre-empt a fix,
This is another 'side of the road joy of discovery' thing. Suddenly stops - cause is leaking hose from fuel pump outlet, but takes a while to find it as the core problem. Either old perished line which cracked or some numbskull put efi hose on, not realising it is also the OUTSIDE that needs to be fuel resistant, so it weakens and the hose clip lets go - use the right 'full immersion' hose and all good.
 

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Oh, nobody has mentioned fitting a Power Commander 3 and getting it dyno'd on. Done properly, the bike will pull smoothly from 1.5k, as opposed to 3.5 / 4k where standard Ducati tune pulls from. Weird but true, more mid-range torque and means you can stay a gear higher and not lock up the back wheel so easy. For which we have slipper clutches - not the 48T STM which only lasts 20k km. If you don't want a slipper, do the 'quiet clutch' mod (add a friction plate to bottom of the stack to lift the pack off the inner hub, Google it), triples basket life and so much more civilised to ride.
 

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Hey, re your q about ecu connectivity, there is a way. I have it in the shed but honestly, since resetting the throttle position sensors correctly once (and the dealer can do that, quick and cheap) I have never felt the need to connect it up again. It was a hand made kit by 'Fast by Ferracci' and no idea if they are even doing them any more.
 

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Oh, nobody has mentioned fitting a Power Commander 3 and getting it dyno'd on. Done properly, the bike will pull smoothly from 1.5k, as opposed to 3.5 / 4k where standard Ducati tune pulls from.
I think he has solved that problem with the 43T rear sprocket. If I recall correctly, the OEM rear sprocket for the ST4s was 38T, which was not good for cruising at most North American street and highway speed limits or starting on hills. The engines don't start breaking in until about 12,00 miles; after which they will run a lot smoother at lower RPM's.
 

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I think he has solved that problem with the 43T rear sprocket.
Until you have tried it, that is a guess, and wrong. The original stupid 38T socket selection was (apparently) to pass drive-by noise testing regulations. Personally I have gone to 14/42 because I am pillioning most of the time, so effectively making 5th into the new 6th and getting a better spread of ratios under that - and now max out at about 245k's, not caring that I can't hit 255 down the front straight at Eastern ck any more. You would think when solo I would not have a problem with torque and these ratios, but to enjoy the snappy butter smooth pull from 2k in third out of a hairpin is quite the experience. Can get a bit 'punch-drunk' on that with the right set of hairpins, as opposed to the greater (but worthwhile!) effort to keep it all humming as a stocker but breaking up the rhythm a little.

Further to battery discussion earlier, you are going to get caught out eventually. A simple mod is to add an extra starter cable to the positive terminal and arrange it so it is really well insulated at the end, it curls up just inside the fairing air vent, so it can be easily fished out for either a jump start (eg if you fit a slipper and don't have anywhere to get to 25km/hr to bump start it) or can make it home by ockey-strapping a car battery to the seat / rack and make it home if charging system cacks itself.

A 16 cell AntiGravity YT12BS-16L lithium battery (16 cell) is a great fix to all battery ills - I finally got around to fitting one of these this week because it allows me to run the heated clothing for wife and I for a lot longer before the woeful alternator capacity is overcome. Fit at least a voltmeter so you know what is going on, but I also fitted an ammeter to see what the state of play is in what is going to happen and how soon. Very important info in outback Oz and has allowed me to limp home in a safe way before with a partially failed reg/rect, vs. straight risk of getting stranded a long way from nowhere. I put an 8 cell AG in a WR250 trail bike 8 years ago. Haven't started it for 4 years but Yuasa battery cacked itself so optimistically put the glorified cream donut size and weight AG battery in the Duke and it started instantly, wow eh. Then realised that a 16 cell (same size as std battery, 1/3 the weight) would allow the heated clothing not to have to be 'time to turn mine off at about 11.9V, typically about an hour into a trip' if I put one of these AG batteries in, so we will be seeing how that goes in a bit over a week with a weekend away coming up. I expect to be impressed!

Why do I know all these things? Guess it's the 400k plus km I have racked up on ST4S's over 17+ years (yep, coupla whoopsies in there too). A great bike and worth fixing the niggling stuff. I contemplated an upgrade to a 2016 Multi S, handed the keys back and zero interest in taking such a cut to riding pleasure in order to get a hit of Multi-Mediocrity. Give me the knees up pin-sharp handling, charismatic 'grandpa's racing armchair' feel of the ST4S over a chook-chaser for grown-ups any day!
 

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Replace fuel filter and lines inside tank and out. Desmotimes can send a kit out to you.
Rear sprocket change is good but going smaller on the front seems to me would add stress to the shaft bearings and maybe more stress on the chain so I never go that route.
Enjoy 😉
 
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