Ducati 620 Sport Base Runs, Mufflers, Etc
The main difference the fuel injection brings is the shorter inlet manifolds and larger 45mm throttles, compared to the old 38mm carbs. Both these features contribute to the improved top end performance, without reducing the lower end performance as happened with the 750 and 900 models when they went to fuel injection, although the cam timing also comes into play here.
The bike is perhaps a little let down by its suspension for serious sports riding, but thats the nature of where the model is aimed I guess. Still very good fun to ride, and it surprises most who ride it with its enthusiasm.
Next well add some lambda curves. First up is std in green, slip on mufflers in blue and slip on mufflers with idle trimmer increased 10 points in red. Fitting the slip on mufflers hasnt really made that much difference to the lambda curve, leaning it somewhat at the top end, but not significantly. I expected that increasing the trimmer setting (the trimmer is used to set the idle mixture trimming up to suit mufflers, etc, is a bandaid solution for a too lean condition) would increase the power output (see the 800 report), but really didnt make any difference power wise. So Id have to say here that fitting slip on mufflers doesnt upset the fueling enough to be of great concern at WOT. How it affects it at lower throttle openings is another thing. Duane did test and remap a 620 on his US trip, and this bike made about 5 more hp with his U59 ECU compared to the std ECU. The owners were also very happy with the improvement. So, as usual, the WOT dyno run doesnt tell the full story. Given the 620 has the same intake and exhaust systems as the 1000, you would expect it to be far less demanding of, and less effected by them.
Now the same with slip on mufflers and Ducati Performance air filter kit. Green is all std, blue is mufflers and air filter kit, red is mufflers, air filter kit and trimmer increased 20 points. Again, adding the open airbox lid hasnt made a huge difference to the lambda curve, and adding the 20 points on the trimmer has obviously richened the mixture without any difference to the power output. Apart from the odd "off the line" feel with the air filter kit, the bike felt quite good with this set up. But, pretty much all the 5.9M ECU bikes, especially the 620 and 1000 bikes I used as transport for a week, felt very nice in all std trim fuel mixture wise.
The next graph shows the changes with fitting the air filter kit, all other things unchanged. Even though the engine makes a little more power without the lid, it doesnt make much difference to the mixture surprisingly. Green is std air filter, red is Ducati Performance air filter kit. The fact it doesnt make much difference is a bonus in the sense of required mapping changes (or lack thereof). Whether or not the open airbox lid changes the part throttle fuel requirement due to changes in inlet tuning effect is something I dont really know. Cant imagine it would really.
The next graph shows the 620Sport with slip on mufflers compared to my 600M with slip on mufflers. The top end increase is pretty hard to ignore, but the 600M really responds to mufflers in the mid range, explaining the similar output there. 620Sport in red, 600M in green
The final graph is a road speed comparison for the 620Sport and 750SS ie. Both with slip on mufflers and air filter kits. With shorter gearing, the 620 is not very far at all behind the 750, an impression I got fairly quickly when riding the 620. On the road, the difference would be fairly minimal in general performance terms I would think. 750SS ie in green, 620Sport in red.
So there you have the little 620. It really is a surprising engine. Once again the combination of shorter duration cams with a little more lift and bigger valves has worked wonders over the whole rev range, with the addition of fuel injection topping it off.