Ducati 998S

The new Testastretta engine finds its way into the std models for the 2002 model year. The 998S that everyone except those in the USA gets has the same engine as the ‘01 996R. The ’02 998R has a bigger bore/shorter stroke 999 engine.

The S is the replacement of the 996S model, itself a sort of de-spec’d replacement of the 996SPS series. So the 998S comes with a 998 Strada chassis and the hot engine. The way most people like it.

Having ridden a few 996R and 998S bikes over the last year or so, I must say I was a little let down by their performance. Although it’s a while since I rode a 996SPS we’d played with, the new model just didn’t seem to have the go that these bikes have. I stopped in at Arthur Davis’ shop on a trip north earlier in the year, and Arthur was commenting he had a customer who had gone from an SPS to a 996R who was saying the same thing. It was therefore in bits getting some work. Not having had the chance to dyno one meant I didn’t really have any idea of how they compared.

Well, now I have. The graph below shows a std SPS in green against this std S in red. By std I mean Termis and chip/ECU as appropriate. No one ever brings me totally std bikes. The curve wasn’t a total surprise though. Once I got to ride a couple of 998s with more km on them, I realised there was a pretty serious top end increase, but you had to see 9,000+ to find it. Also, the 135 hp of the S is a bit misleading, as it is really 133 until a spike as it hits the rev limiter. So, finally, a Ducati with some serious top end hp. The bump in the torque curve @ 7,500 RPM is where it really starts to boogy.


Dynograph courtesy of DYNOBIKE (03) 9553 0018

I thought at this point that a comparison table might be in order. Dimensions in mm, cam timing @ 1mm lift.

MODEL
BORE
STROKE
VALVE DIA — I/E
VALVE LIFT — I/E
INLET TIMING
EXH TIMING
THROTTLE DIA
996 SPS
98
66
36/30
10.8/9.8
14/73
57/23
50
998 S
100
63.5
40/33
11.7/10.1
16/60
60/18
54

Bigger valves on both inlet and exhaust, run by cams with less duration, but more lift. Both models run 50mm exhausts and the same air filters/runners. The larger throttle bodies of the 998 series, which use shower style injectors, give more airflow for any given throttle opening. This has a couple of effects. One is that the bike will make more power with, say, 1/4 throttle than a 996 did. Simply because it’s getting more air. The benefit of this is really nil ( often a little less "rideability" ), but it makes the journalists say things like " much more responsive ", as they really don’t understand this kind of stuff. Which is why they always said the Aprillia RSV, with its 60mm throttles, was more responsive than a 996. Obviously. For the 2002 year, Honda went from 52 to 60mm on the RC51, probably with a similar response from the journos.

The second effect is more flow area at WOT. Which is the point. Not sure how much it has to do with SBK homologation these days, but it was probably a good idea anyway.

The other main change is in ECU. The new models use the Weber Marelli 5.9M, like the Monster S4 and ST4S from 2001. It actually seems that all the 2003 models, except maybe the ST2/4, use this ECU. Very compact, and using Flashload technology ( like the 1.5M of the SS/M ie ), it is at this stage unbroken. There is a couple of add-on dial boxes available that I have seen, but I frankly wouldn’t bother pissing on any of those if they were on fire. A Power Commander hasn’t appeared yet, nor has FIM been able to get into it.

Although, Duane is working on a replacement ECU that will be fully adjustable, using software similar to that for the 1.5M. It is running on his S4 as I type this, but he still has much pre production testing to do before he can sell it. It will be visually much the same as the std piece, with the same connectors. You just remove the std ECU and fit the FIM unit.

This wasn’t much help to me though. There is one way of playing with the fuel on these, coming to my attention via a service bulletin from Ducati Performance, of all places. It’s not the best way to do it in any sense, but for now it works. It worked very well on this model, although I’ll no doubt get too cocky on something else and get slapped for it.

That’s about all in real terms of changes, as far as I worry about. The bottom end is a bit different, with the S getting the deep sump that looks so race, but in reality it’s still just the glorified Pantah the old engine was.

My task here was to get some more out of it. First time round it’s always a bit of a guess, but in this case the lack of fuel adjustability compounds the issue.
So, back to the story. I pulled this one apart, checked and reset the valve clearances as the owner had requested, then made up some new tools to allow me to check the cam timing. Given all the hype about access, etc, I must say I found this engine no easier to do clearances on. And they’re messier when you have to pull bits off, with oil going everywhere. I hate that.

I had been told the S/R models in particular could be off in the cam settings, and they were right. About the same as the old models, really. The Stradas are allegedly better. I set the new timing to about what I thought the fuel adjustment I had would allow me to run happily, reassembled and went to the dyno. After a few runs, I had the result below. Not too bad at all. The increase @ 6,000 RPM is around 12%, something the owner noticed pretty quick. The fact the top end stayed as it was comes down once again to a good first up guess. When I get a fully adjustable ECU I may try different settings, but for now this has worked just fine.


Dynograph courtesy of DYNOBIKE (03) 9553 0018

The only thing I was concerned about with this one was losing fuel economy. This bike hadn’t been setup after the owner installed his DP Termi and ECU kit, and was a bit lean at idle. This effected the fuel economy he was getting before we did the job, which was far better than his 996 ever got. After it was still slightly better than his 996, so he was still more than happy.

Other benefits he reported were the usual increases in response and smoothness. No surprise there.

For a comparison, below shows the result against the after for the same 996SPS as the top graph. The new engine, with its bigger valves and shorter cams, enjoys a small mid range advantage and the same top end as before.


Dynograph courtesy of DYNOBIKE (03) 9553 0018

Funny thing is though, I only got to ride this bike 2 or 3 times after I did the job, and even then it was starting to feel a bit soft again. Amazing how fast your brain catches up sometimes. The new engines are much more flighty too, and will lift the front wheel far quicker than the old engine, even in std form. I was going to fit a machined down flywheel, but with the light crank and ti rods, they already seem pretty light. No doubt someone will want to try it later.

So I must say that now I am quite impressed with the new engine. I had my doubts early on, but the new Testastretta are now the most sporting engines Ducati has ever produced. Smooth and tractable, with good power all through and a real top end.

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