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Discussion Starter #1
I had my belts replaced yesterday. They had about 5k miles on them but were going on 3 1/2 years old.

The local dealer has always been very fair to me (this is not my first Duc), he charges a reasonable price for Ducati belts and 1 hour labor (@$95). I made an appointment to bring it in (between thunderstorms here in North Texas).
The mechanic seems to enjoy Ducati owners and lets me hang with him while he works. I don't overdo it.

The ST4s is new to me this year, the previous owner lavished much on the bike and it was loaded with farkles, including the DP airbox/pipes and I assume chip.
It is a 2004. Has only 13000 miles on it and runs like a scalded cat. Fast and strong everywhere in rev range.

So the belts were changed and he asked if I wanted the service bar turned off. Sure I replied.

He finished, I paid and I headed out to meet wife and daughter at lunch (about 25 miles away).

I started noticing things

seemed louder primarily through intake tract

was not as punchy in lower mid range (was in traffic so I couldnt rap it out). A little stumble off idle.

and as I rolled to a stop a slight whistle winding down.

I called the dealer from my lunch location. The mechanic told me to bring it in if I wanted and he would check it out.
Big storms were threatening (again!) and I didnt feel like riding 50 miles in the condition, another day if need be.

I asked him if he touched the mixture (trimmers). He said no. All he did other than the belts was check the plugs (perfect he said)
and reset the service indicator (including an old error code the bike sent sometime in the past). He used the Ducati computer to set belt tension
and said sometimes they can make a little sound initially I might be calling a low pitched whistle.

My concerns are

are belts correct, could he be a tooth off and still not damage the engine (and why the intake roar)

did he somehow replace the DP map with the stock one?

any insight would be appreciated.

bob
 

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Discussion Starter #2 (Edited)
finally a nice break in the weather in Texas. Took the bike out for a good ride.

For sure there is something amiss. The engine is significantly down on power. Seem like when I add throttle I get noise, not acceleration, at least not what I was getting before. I pulled the tank up and looked for anything amiss.

I'm going to assume the belts are correctly installed and the valve timing is correct. I would assume if wrong I would have a serious issue.

The only thing that comes to mind is when the mechanic reset the service indicator, he checked for error codes and reset one. I somewhere remember (possibly) that the DP setup changed the way the injection worked and shut down the closed loop of the fuel map. Could he have reset it to the standard map.

I'm really out of my depth in fuel injection, I've been a carb guy forever!

Bob
 

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The only thing that comes to mind is when the mechanic reset the service indicator, he checked for error codes and reset one. I somewhere remember (possibly) that the DP setup changed the way the injection worked and shut down the closed loop of the fuel map. Could he have reset it to the standard map.
No.. he could not have loaded the standard map back without intentionally doing so with special equipment and the ECU has no ability to do that on its own. That is definitely not the issue.

Have him be sure he is not off a tooth somewhere. Easy to do. I always double and triple check before buttoning it up.

Some what ifs...

What if the original owner used the slick adjustable cam wheels Ducati started adding in 2001 to degree the cams to optimal settings? What if that owner made no markings to indicate that was done so anyone else working on it later wouldn't screw things up? What if the guy who did your belts loosened those adjustable cam wheels and locked the fixed backing plate like it says to in the manual when setting belt tension? If he did, he just "unset" the work someone did to optimize the cam timing. Simple enough to ask him if he loosened the cam pulley adjustment screws when he set belt tension. Most of us home brew guys don't mess with it, we just do belts as if they were fixed pulleys. Many who are so inclined will use the feature to degree cams without needing offset woodruff keys. If you have contact with the original owner I would ask if he, or anyone working on the bike for him, degreeed the cams.

This is total speculation on my part... Please don't assume this is what must have happened. If you trust the guy that did the work, just bring it back to him for a look. It could be as simple as being off a tooth somewhere. Is the bike smooth or running like maybe the TBs are out of sync?
 

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Discussion Starter #4
Good idea on reaching out to the original owner.

I had no idea overlap changes would be so dramatic, it was the strongest ST I've ever been on. It's no longer.

So the belts can be off a tooth without valve hitting piston?

Bob
 

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Discussion Starter #6 (Edited)
Dealer is closed on Mondays. I have a call in to the previous owner. He was a well off gentleman who held nothing back with regards to his bikes. He had quite a few (very nice) bikes. Quite the enthusiast. Good guy.

Now that i think about it when I called the mechanic the day of the service, he mentioned something about cam timing and did I (he didnt know history of bike) have the cams degreed! Told him I wasnt first owner and that I didnt know if it had been done in past.

I dont want to assume too early, I think he was a conscientious mechanic, so I dont want to be critical. Assuming he followed the Ducati proceedure and reset the cam settings, how difficult is it to go back to where it was. If it was reset back to factory settings I'm confused. I can't imagine Ducati releasing a bike with my current settings. It's just not a little down in power, its significant...

bob
 

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how difficult is it to go back to where it was.
If this IS what happened, then going back would involve degreeing the cams as you would from "scratch". Unless you got lucky and whoever did the work made some obvious paint marks that you could trust replicating.

If it's as much a noticeable difference as you are describing, I'd wouldn't leave anything off the table except that the OEM map was somehow restored. Are you sure there is no Power Commander installed that maybe was somehow disconnected? Running on both cylinders? TPS set wrong (did he mess with that?)?

The cam timing thing was just a thought, but it is a good possibility given work was directly done to the bike that may have affected the timing if the cams were previously optimized and the current mechanic went by the book.

Here is the 2003 service manual. You'll need to download it.
https://www.dropbox.com/s/nq4l11qhsc0lvij/Ducati%20ST4s%20ST4s%20ABS%202003%20Full%20Workshop%20Manual..pdf?dl=0

If you go to section D4, starting around page 15 of that section, you'll see a nice graphic description of how to tension belts using locking tools and the movable cam wheels. The locking tools lock the crank and cams into position. The movable pulleys are supposed to "not" cause timing errors due to the influence of belt tension inaccuracies (or some such bull crap). In theroy, if you are going to degree your cams, even with these nice adjustable pulleys installed, you are supposed to still use offset woodruff keys. You can see why people would use the pulleys here instead of the off set keys. No problem, unless it's done that way and then someone not knowing any better goes and actually "follows the new directions" to tension the belts and screws it all up.

I don't do mine like the manual. I just pretend they are standard non-adjustable pulleys and set tension like before. No problems so far, but who knows, maybe mine is down on power... Haven't been on another ST4s to compare.
 

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Discussion Starter #8
Just went through the workshop pages you sent. I see now how it works. Different than 2 valve.

Thanks,'

bob
 

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Discussion Starter #9 (Edited)
At dealer, yepper they changed the cams to stock marks.

They spoke to Ducati, and Ducati suggested to look for SPS cams also.

Apparently the bike runs so bad in midrange on stock settings, they suspect it has performance cams.

They are going to keep bike for the day and put it back to where it was before.

Bob
 

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Interesting. Good luck and please let us know what you find. Any info from the prior owner?
 

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Why in the world would he have done that!! Horz on TDC, sprocket lock on vertical cylinder.....change the belts!! Why mess with the sprockets? Hope it gets sorted out ok for you. Good luck.
 

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Discussion Starter #12 (Edited)
Unfortunately he's (previous owner) out of the country.

The shop was working with Ducati to figure out what the cam timing should be.

They were willing to put the hours in to re-degree the cams (which ever cam I have!) .

Bob
 

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Discussion Starter #13
Why in the world would he have done that!! Horz on TDC, sprocket lock on vertical cylinder.....change the belts!! Why mess with the sprockets? Hope it gets sorted out ok for you. Good luck.
I asked the same question. Apparently it is the normal proceedure to loosen the cam sprocket to equalize the tension between toothed sprockets. I see that now in the shop manual SS904 sent me. But when the movement to adjust is a significant amount they should ask the owner before proceeding with a significant adjustment. The shop owner was apologetic and promised to correct everything.

Cant complain, shit happens i guess.

bob
 

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Hate you had to be the guinea pig on this one, but it looks like there is a noticeable bit of power if someone takes the time to dial in the cams.
 

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Discussion Starter #15
hehe, hated to be the guinea pig on this too.

But I can tell you for certain this bike when running properly is fast. My son rides a cbr1000rr and I think on the street the Duc is quicker. BIG power in the mid range. At upper rpm toward red line the Honda is faster, but he has bragged on the Duc (riding on the street) and he's a total Hondaphile.

I dont know what cam it has in it and if it has the SPS cams it may explain some of the difference.

bob
 

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Discussion Starter #17
One of my pet peeves is to have a troubleshooting discussion with the OP not providing the outcome.

My bike is fully up to speed, in fact, someways better now than before it went in the shop

The dealer (Eurocycle-Ft Worth) did all he promised to do. Entirely on his nickel to be clear. I couldn't be more pleased.

Ducati got involved and helped in providing guidance and solution.

My bike apparently was an interium design that Ducati built for just a few years. None of the existing tool sets for timing cams were in the dealer inventory. He ordered the appropriate set even though Ducati only built a limited number of this interium engine.Once the proper tools were obtained, the cams were set up and the engine became wonderful again.

In fact the engine off idle is far more stable. It used to require a little clutch slipping to get underway and on acute angle turn backs it was a challenge to keep the engine on the boil. now it's rock solid feeding out the clutch and pulls strongly from idle.

Drivability has measurably improved.

All is good now.

Bob
 

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Fantastic outcome.

I'd be interested to know what's different about your model.
 

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Discussion Starter #19
the difference is all in the cylinder head. There were some casting differences. Why I don't know?

Bob
 

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Hmmm. The 4V ST and Monster had a head that differed from the Superbike head in that the exhaust cam end is cast lower to fit the more compact ST frame (which all Monsters had starting with the S4). Result is shorter belts, shorter exhaust valve stems and some other parts different like the rocker pin side plates. The timing marks are also different, which is probably key here. I hope that's not what they mean, as that head was used from the original ST4 through the final ST4s second gen models and the Monsters until they started using the Testa engine. Last year of the 748 had it too. That head is hardly a rare item, so now I am curious.

Going to have to dig for a little info on this one...
 
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