750 SS IE : MUFFLER, AIRBOX AND ECU MODS

The smaller brother (sister?) of the 900 SS IE, I was expecting some real improvements from muffler and airbox upgrades. Unfortunately, it would seem that the standard muffler’s flow capacity works just fine for the 750. As with the old 900, there is a midrange improvement, but much the same top end. The advantage is more in the riding, as these bikes are much improved with a set of mufflers. Quite a sweet little bike to ride, once you get used to the lack of outright power

This first graph shows a standard bike against the same bike with some DUCATI PERFORMANCE high rise mufflers and ARROW standard style mufflers. An ECU upgrade from FIM was flashloaded in for both pairs of mufflers. This is not quite what we were expecting, given how better aftermarket mufflers make these bikes feel. The curves are standard in green, ARROW red and DP blue. All the following curves are plotted against road speed, with the engine being run into the rev limiter on all runs.

We did find a touch more power in the DP high rise, however, with a slighter leaner WOT fuel curve. This is shown in the graph below, with the leaner map in green, the original map in red. Whether you could feel this on the road, though, is another matter.

Next we removed the airbox lid. This added the expected amount of power. The leaner WOT fuel curve added a touch more power again, but the difference was smaller. This indicates that removing the airbox lid has leaned the mixture a little, but not a great deal. Certainly not enough to worry about. Green is lid on, red lid off and blue leaner map, lid off.

So, comparing the best ( DP high rise, airbox lid off, FIM leaner WOT fuel curve ) with standard we get the next ( and last ) graph. As usual, best is red, std is green. On the road, response would also be improved. The aftermarket mufflers also tend to smooth out the lower end power delivery.

How this model will respond to the normal cam timing mods remains to be seen. I would also really like to try some 900 carb model cams in these engines. I have seen these heads make 73 Hp on a different engine, so there is certainly some left in the750. Just depends how many revs we need. I also hear of some further mapping changes that bring real gains.

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