Ducati 800 Monster: Base runs, Mufflers, etc

The new midrange model for 2003, the 800 comes with the same updated 2V tuning that the 620 and 1000 have from the factory. Namely bigger valves and
shorter duration cams. The improvement over the 750 is quite marked, and puts this bike rather close in terms of performance to the now superseded 900
model. So, for the second time in Ducati history, and after the fourth incarnation, we lose the 900SS.

The 800 was something of a surprise for me when I first rode one. Giving it the usual "see how easily it lifts the front" test, I was amazed with how it responded. Much like a 900 really. So I was keen to get one on the dyno.

For a full rundown on the changes made from 750 ie to 800 ie, check the "Comparison of 2V Models" report, but, in short, they are:

• Longer stroke – from 61.5mm to 66mm.
• Slightly higher compression
• Bigger valves – increased 2mm on inlet, 3mm on exhaust to the old 900 sizes of 43/38.
• New cams with similar duration, but revised inlet timing and more lift.

So, to the first graph. This is the shop demo 800M ie. Green is all std. Blue is with some slip on mufflers and the idle trimmer increased 10 points. Red is with slip on mufflers, DP air filter kit and the idle trimmer increased 25 points. This shows 73 Hp std, and 78 Hp with the (not fully developed) mods. Very cool. Power first, then torque.

Now some runs for the steps taken with air/fuel mixture curves. Again, green is std. blue is slip on mufflers fitted with no other mods. Red is with the idle trimmer increased 10 points to richen the mixture. As you can see, fitting the mufflers has quite a big effect on the mixture – much more than on the 620 – and puts the WOT mixture into the too lean area. Increasing the idle trimmer 10 points – just a guess on my behalf – certainly helps the power output. But in mixture terms, this is still no where near enough for max power. Generally the fuel for best "on road" power is about 5 – 8% richer than the best "on dyno" power, and there is more to come before best "on dyno" power is found here. The difference between the blue run and red run is significant enough for me to know there is more power available with more fuel. We could use the idle trimmer to try to find it, but with the air/fuel still above 13:1, and closer to 14:1, I doubt we’d get a satisfactory result, with the richer trimmer causing excessive low speed richness. So, I can only say that for best performance, even with just some slip on mufflers, some sort of re-mapping will be required. Using the U59 ECU from Ultimap would be the way I’d be heading.

As you can imagine, if fitting slip on mufflers only puts the fuel out the window, fitting the Ducati Performance open air filter kit only makes things worse. Not too much worse, surprisingly, but bad to worse none the less. The next graph shows the results. Green is all std. blue is slip on mufflers and DP air filter kit. Red is slip on mufflers, DP air filter kit and idle trimmer increased 25 points. Again, increasing the idle trimmer has made a noticeable difference, but no where near what is required. So, I couldn’t really recommend fitting the DP air filter kit with the std ECU, even with the idle trimmer cranked up, as the amount the idle trimmer will need to be increased will cause "too rich" problems at low throttle openings. Or "idle too high" when the air bleeds are wound out to compensate. Not that that will stop many owners I’m sure, as many will just fit the bits and ride away. The few who try to compensate with the idle trimmer and air bleeds will also happily ride away. What I can confidently say is that, with a well mapped U59, this will certainly be a much nicer thing in this state of tune.

The difference in air/fuel mixture due to the DP air filter kit is shown below. Green is all std. Blue is slip on mufflers only. Red is slip on mufflers and DP air filter kit. The change in the air/fuel curve from blue to red is not that big, and echoes comments Duane made after his US testing, where he found the 800 didn’t need enough more fuel running an open air filter kit to justify making a specific map for it, distinct from the "slip on mufflers, std airbox lid" map. Surprised me, but when I saw this result I certainly believed him. The change in mixture from std to slip on mufflers certainly shows the restricting effect of the std mufflers for the 800 engine. Thinking about it now, I would like to see the curve for open air filter kit and std mufflers, but I wasn’t thinking about that at the time. Usually with these models, opening the inlet has far more effect than opening the exhaust. With the SS/M ranges sharing the same pieces on the inlet from the outside air (almost) to the manifolds, and the header size and mufflers on the exhaust, I imagine the 1000 will really improve with some added flow in and out.

Next a comparison with the past. Green is std 750SS ie. Blue is std 900SS ie. Red is std 800M ie. The 800 is far closer to the 900 than the 750, and it‘s quite hard to believe it’s only 7% bigger than the 750, and 12% smaller than the 900. It should be very obvious from this graph that the bigger valve/shorter cam thing is a winner.

Next a comparison between the 800 and 900 with slip on mufflers, DP air filter kits and more fuel. In this case, the 900 has a "reflashed" ECU from Ultimap, where the 800 has the idle trimmer cranked up 25 points (as seen previously). Here they are far closer, and would be even closer still with the 800 mapped correctly. Given the 800 has a 6 speed gearbox with a similar (slightly smaller) ratio spread, I would expect an opened up 800 would go very close to matching an equivalent spec 900 on the road. Wouldn’t be much in it at all.

So, that brings us to the end of this initial 800 report. If you’ve picked up that I’m pretty impressed with this engine, you’d be right. But, as an engine guy, it’s a little frustrating that the 750 they’ve dropped was produced with so much less potential for so long. There are quite a few mid 70’s Hp 750 around running the older carb model 900SS cams and 900 43/38mm valves. It’s not so much that the 800 is good, but that the 750 was bad that annoys me. In power producing terms, this has far more to do with the 800 being right, and the 750 just plain wrong. I’ve been trying to find ways to get the 750 to go better for not too much effort or expense (that there will be reports on), but the real problem lies with the combination of cams and valve sizes and the fact that replacing one or the other will help somewhat, but replacing both works wonders. And going big valves and other cams (the tricky part is getting cams that work well) is both expensive in parts and time and, being realistic, you’d just buy a bigger bike. Meaning very few owners really get into modifying 750s.

So now, instead of just saying "buy a 900", we can say "buy an 800, or 900, or 1000".

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