1098 With Termi 70mm Full Exhaust Kit and Cam Timing Changes - Written 10/07, Update 04/08
1/ Full system before and after.
Well, I thought the last 1098 was a bit disappointing. This one was a bit better in terms of all std power, but the improvement with the full system left us a little surprised. I don’t know where the power is, maybe the DP Carbon Termi muffler kit is where it’s hiding.
First up this bike as compared to the previous report bike in all std trim. Both had around 1,000km on the clock when dynod. Green is this bike, red the previous. Clearly this one is better, why I don’t know.
Next is before and after full system. The given max power for the after run is a bit misleading, as the spike at the very end is higher than the peak at 10,000 RPM of 142.2 Hp. Certainly not like I was expecting or hoping we’d see.
We didn’t get a decent before air/fuel trace (often hard with std mufflers) so the next run is after power and air/fuel graph. While there’s a bit of variation in the mixture I wouldn’t expect there to be more power anywhere with a flat 12.7 or so.
If we compare the after runs for this bike and that from the previous report (and keep in min the baseline power difference) it would appear the slip ons have a lower RPM power advantage, and maybe not much of a higher RPM disadvantage. I would like to dyno a carbon Termi slip on kit as they are open mufflers unlike the Ti mufflers with the cat at the front, but haven’t got to one as yet.
2/ Cam timing before and after (full system already fitted)
I had read that 1098 ‘as delivered’ cam timing was no better than previous models, and had an owner keen to get his checked. The 1098 base spec cams are about the same as the 998/999S model cams, with a little more lift. Plus the 1098 valves are bigger 2mm on the inlet and 1mm on the exhaust, the same as the ’05 999R. The table below gives the specs.
Update 04/08: since I did this bike I’ve been told by staff at the Australian importer that for Superstock racing Ducati were recommending advancing the inlet cam 8 degrees over spec and retarding the exhaust cam (I think, I forget now) 3 degrees over spec, which would give 103.5/107. Although there was an article about the bike that won the European championship in Australian Motor Cycle News where the rider said it had too much midrange and he had to rev it high all the time to stop it wheelying. Which is a somewhat amusing example of what varying cam timing can do to a bike in a specific application that’s not exactly helpful.
The bike we checked was delivered with 117.5/106 on the vertical cylinder and 115.5/107 on the horizontal cylinder, meaning the inlets were retarded 6 and 4 degrees, the exhausts retarded 4 and 3 degrees. The cam timing for the Testastretta engines is spec’d with the timing belts at running tension, not over tight like the Desmoquattro were. The first 998S I played with I set the belts over tight like I had done previously, and used 107/107 timing. With the belts at running tension the timing is usually about 2 degrees advanced as compared to the over tight tension, so with that in mind and the similar cam specs and bigger valves I ran this bike at 105/109.
This gave changes of 10.5 and 12.5 degrees on the inlets and 2 and 3 on the exhausts, with 8 and 9 degrees more overlap. The cranking compression went up from 185 to 210 with the cam timing changes, and when setting up the balance and mixture we leaned the idle trimmer off slightly from +25 to +21. The idle mixture was set with one air bleed full in and the other wound out as required to balance the mixture the idle control valve takes care of the idle speed. Riding to the dyno for the before run it was clear it was way too rich on cruise, hunting and generally not pleasant at all. After it was better, but I’d like to try running it a little leaner again to make it nicer all round. Stalling issues not withstanding, of course. I don’t know yet if I’ve exaggerated that or not.
I dynod this bike before hand and the curve was very similar to the first bike shown above, although this bike was quite a bit richer. Green is the previous bike, red this bike.
So this at least confirmed the previous bike’s output as being representative. We went back after the cam timing changes and ran it again. Green is this bike before (red from the previous graph), red after the cam timing change. The improvement is pretty much as expected, and still with the midrange hole. Power first, then torque and air/fuel.
It’s still a bit rich, but acceptable in the grand scheme of things. I have no idea about the little dip at 3,500 RPM, although I guess the lean peak just over 4,000 RPM (allowing for the Dynojet’s usual 500rpm or so lag) could be a cause. The power is still flat at the top end, so maybe you could go a little further with the inlet advance.
Overall I’m finding the engine character of the 1098 a bit disappointing. It’s almost the same as the 996/1026 job we did it came on really hard around 6,500 RPM like no other 4v I’d done, but under that it was just flat. The 1098 is the same. The torque rise between 6,000 and 8,000 RPM will probably catch some people out, and it makes it hard (for instance) to consistently wheelie it.
As the revs increase, the torque increases so the front comes up faster the higher it gets. I’m sure if I had the chance to get used to one I’d be impressed with the top half of the power band and be pulling very nice multi gear wheelies. But I also wouldn’t have a licence to be able to ride it, and given our state’s new laws, there’d also be a seized and auctioned 1098 and a somewhat unimpressed Hunnybunny.
Getting back to the flat midrange - personally I’d speculate that it’s exhaust related, and given what I’m being told about the Aprilia V990 old and new style models I’m starting to get into, I think it’s exhaust style rather than size. Although I do think 70mm is too big.
Specifically the long single pipe section, as opposed to the twin pipes with good crossover from the 996 and 998 style chassis. The 999 full systems share the same long single pipe section, and a 999S with a full system (54 or 57mm) shows the same (comparative) lack of midrange as a 1098. A base model 996 with the cam timing reset and tuned to suit makes more than both under 7,000 RPM. I did another one of them very recently too, and they definitely feel better down low.
Although, having said that, the S4Rs Termi full system gives a similar hole from 5,000 to 6,500 RPM, and it has a twin pipe with cross over style system. So maybe I’m talking crap again.
Anyway, the next graph shows this 1098 in green, a 54mm full system 999S in red, a big valved, 54mm full system 999S in blue, a 998S in yellow and a 996 in pink. The 1098, 999S and 998S all run the same 107/107 (105/109) cam timing, the 996 108/108 cam timing. The 996 gets creamed at the top end due to its little valves, but the 1098 should be 10% better in the midrange due to its 10% greater capacity. It’s not, and that’s disappointing.
I must say, however, that the new head design is much better from an ‘oil pissing everywhere when you remove the rocker covers’ point of view. 749 and 999 really annoy me with that, and they’re so hard to get it all off of. And now if you need to remove the rocker pins to get the opening rockers out you can just undo them. Try doing that with a 749 or 999 and those bloody side plates. Hello “my bike didn’t leak oil or coolant before you worked on it”. Oh yeah.
I think I’ll stop now.