ST4S With Ducati Performance Power Kit

Being the "complete with ECU" power kit from Ducati Performance, it also includes some Carbon mufflers, open airbox lid, washable filter, 14T front sprocket, 37T and 39T rear sprockets. Std gearing is 15/38. There was previously a kit available that was only mufflers, airbox lid and filter, but that now seems to have been replaced.

For those not aware, the ST4S is a little different from the ST4 in terms of engine management. Although it is still the old "Desmoquattro" 996 engine, it shares the reduced duration inlet cams with the S4 Monster and the new 5.9M ECU – the very little one. This ECU has no replaceable chip, and as yet there is no remapping facility available. FIM are working on a replacement ECU that will go straight in and work the same as the std one, apart from being adjustable using software very similar to the 1.5M ECU (SS, M ie) customising software.

For the moment, however, the only options are to use the idle trimmer to richen or lean the whole map, or to replace the ECU with another. Ducati Performance has been selling ECU in kits for S4 Monsters, but the ST4S kits had the ECU dropped when first offered. Instead, the original kit came with instructions to set the idle mixture as per normal, then once done to increase the trim by 20 points and wind out the air bleeds to lean the idle mixture. I have used this idea to richen a 998, but it really isn’t that flash, particularly when you need quite a bit more fuel. So I was quite keen to test this combination, just to see how much difference the ECU made.

So, to the curves. The first graph is power, the second torque. This bike was a little lean on the idle trimmer when I dyno’d it, so all the results are leaner than I ended up setting it, but the results and the improvement offered by the remapped DP ECU are very obvious.

Green is all std. Blue is with the Ducati Performance Carbon mufflers fitted. Purple is with the DP air filter kit added, but still running the std ECU. Red is the addition of the DP ECU to the mufflers and an air filter kit. From the first run, I knew this ECU was pretty good, WOT fuel wise. The curve was smooth and fat, and obviously far better than anything with the std ECU was. That’s an increase from 108 to 118hp, without even a dip, pulling hard to the 10,500 RPM rev limiter. I didn’t get to ride it, given the leg situation, but those who did, including the owner, were way impressed (it also had the 14T front sprocket fitted). Turns it into a very fast bike, especially for a tourer with panniers.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Next up is a comparison with std 996 and ST4. Green is 996, red is ST4S and blue is ST4. Given the common exhaust and inlet of both ST bikes, the similar shape in the curves is to be expected. The better upper RPM performance of the 996 is most likely due to the better airflow its airbox design allows. Pulling the airbox lid, as shown in the 888 and many other reports, is certainly one way to get the ST series to make some power.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Now another comparison, this time this ST4S with the complete power kit, and a 996 with Termis and FIM chip. Much more equal, and I’d expect the shorter duration inlet cams to have a bit to do with the better output. I really like these cams. Red is ST4S, green is 996.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Now, some graphs showing air/fuel ratio curves and the difference increasing the idle trimmer has. There was a bit of a problem here, however. Had I set the idle trimmer for correct idle mixture on the gas analyser with the DP mufflers fitted and std ECU before hand (which I should have done for correct testing procedure), it would have started at +45 or so. As it was, it started out at +10. I didn’t expect it to be that far off though, and this has greatly reduced the value and relevance of the testing I did. It’s really annoying me now that I didn’t check this before, as I normally would (and did consider). Bad test procedure pisses me off, especially when I’m guilty of it. I was hoping to get a "trim up" figure for slip on mufflers with std ECU, but really just wasted my time. So, all these runs are skewed somewhat by being too lean anyway. Even the std run is with the trimmer set too lean, although I didn’t get an air/fuel trace for the std runs. The effect of the trimmer is obvious though, as are its limitations in correcting the fuel mixture.

First graph is with DP mufflers only and the std ECU. Trimmer set to +10 is green, +20 is blue, and +30 is red. As stated above, the trimmer should have been +40 at least to start with, so if we set the mixture as part of a service it would have been richer than any of these runs. However, even if I had started at +40 and then gone up to +60, I doubt very much the air/fuel trace would have gone under 13:1, as I would want to see it for best power. Which does disappoint me quite a bit. Does this mean running slip on mufflers with the std ECU is bad? Well, we have lots of customers doing this, and no-ones had made any complaints to me yet. Although, I would expect them to feel better on the road with a well developed map, given these results.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Removing the airbox lid and fitting the DP air filter kit led to a not so obvious lean spot (dyno power wise) in the S4 Monster, and has a similar impact here. Not quite as lean, but you can see that increasing the trimmer setting really didn’t have much effect at all. Not sure why it was like this, but running these things lid-less without an appropriate ECU is to me not a good idea. Up to you though.

The graph for DP mufflers with air filter kit is next. Trimmer set to +10 is green, +20 is blue, +30 is yellow, and +40 is red. As you can see, not that much variation between the air/fuel curves for the four settings. The purple run is with the DP ECU added. The difference in both air/fuel and performance is very obvious. The trimmer is set to +20 for this run, although it ended up at +35 when I got back to work and set the idle mixture to 4% CO using the gas analyser. So, it would have been a little richer again than this curve shows.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Just how much is indicated by the next graph. This compares the three runs I did with the DP ECU fitted, plus the richest with the std ECU for comparison. I varied the trimmer setting to see how much difference it would make. Not much. Which really indicates that the mixture is pretty close to what the engine wants. The trimmer may only be adding a couple of percent per 10 points in reality at WOT, but if the mixture is off, any improvement usually helps. Given I went to +35 for the final setting, the air/fuel trace for that setting would have been between 13:1 and 12:1 throughout the run. Just perfect. I have to admit, the DP people are getting far better with their mapping. Although they’d want to be, as this kit is about $2,800 Aust, while the ECU, as an individual part, is available for about $1,650 Aust. Trimmer set to 0 is green, +10 is blue, and +20 is red. Yellow is with the std ECU, and is the ‘red’ curve from the previous graph.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

So, for the final graph, a before/after. While the trimmer settings may be affecting the before graph a little, the rough shape is pretty normal for a bike with std airbox and mufflers. The after curve is just lovely, and really couldn’t be much better. Green is before, red after.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Of course, there’s an ‘of course’ to finish. The DP ECU that came with this kit was that of an ’02 model bike. For a company that made a habit of changing model spec only with new models, the variations between model years of the same bike are now catching lots of us out. Especially dealer staff, who generally only find out some of the more obscure changes when a customer points it out. Leading to a look that means "why the hell don’t you know about this, dickhead". Which then makes for an uncomfortable explanation ("oh. Well, …….").

On the ST4S, the ’03 model bikes – which this particular bike is – can run with the side stand down, as long as the bike is in neutral. It can also be started in gear, but only as long as the clutch is in. which means it has a clutch switch also. Much like the variation between ’01 and ’02 model S4 Monsters. Anyone familiar with the S4 DP ECU debacle will understand the implications of these changes. This ST4S will no longer start or run with the side stand down, even in neutral. It will also start in gear any old time you like.

Now, at this point of time (Feb ’03) the DP catalogues, both printed books and online, do not differentiate between ‘01/’02 and ’03 models. Which means this kit is a single part number for all years of ST4S. Meaning if you have an ’03 model, you cannot buy the DP kit with the "correct" model year ECU.

So, let the wailing commence. I’m sure that this will become an issue that DP will solve soon. Frankly, after the S4 mess, they should be thinking of this stuff up front. This particular owner didn’t seem to give a rats arse about not being able to start on the side stand (luckily ST series bikes have a centrestand) so it was a non issue here, but please be aware of this. You have been warned.

[Top Of Page]

Home | Blog | Facebook | Service Enquiry | Products | Reports | The Dyno | Disclaimer | Contact Us