Ducati 900 MONSTER CARB BRADS FINAL EXHAUST STORY ( A MONKEY FOR MY BACK )
I had a feeling this may have been fuel related, so I wacked in the lambda probe for a quick check. Right again. Now I had a pretty horrible lean spot in the middle. Compare the curves below. Red is for the std headers with some good slip ons, greens is for the modified ARROW TWIN TUBE. Wow. Less power and a jetting problem. Looks like Im on a winner huh.
So I rejetted to suit, pulling the carbs apart once again. Did I mention at this stage I really wanted to just stop working on this bike and sell it? Hmmmmm. So I ended up with the next set of curves. As you can see, the lambda curve is much better, even if the power isnt. You can feel it on the road, though. Red is obviously rejetted. At this point I was starting to wonder if the location of my cross over was the problem. Too far down the header pipes maybe? Just enough to make me go aaaaargh.
So for a final comparison, below is what I finished up with, against what I could have had with a set of slip on mufflers and the standard header pipes. Im sure you know which is which. Just goes to show how good the std headers work, and that I should have listened to Doug all those months ago ( the 900 SS ie that makes 90 Hp uses std headers ). A good output to for that setup, simply being slip on mufflers, cams dialled, jet kit and open airbox lid. A very enjoyable little machine.
The last graph shows final versus std. Bob the Parts King went for a spin at my request for some feedback. His verdict was smooth and strong. Pretty much what I expected. The smooth bit comes from the 35 pilot jets I fitted ( 40 std ). I have done this before to bikes with an open airbox lid, but having my own bike to play with gave me a chance to come to this setup over a period of time. This is one of the reasons I like having my own bikes to play with. I find out why I have done things in the past, and if I have ever disregarded anything I shouldnt have. Turns out things I thought I had overlooked in the past were not important, and I was pretty much spot on. Nice when it pans out this way. This bike is very nice to ride. Almost as smooth down low as the injected version. Pulls top gear very nicely from 3,000 rpm. A combination of jetting that works very nicely indeed.
Pity Im now selling it, but 4 is still too many. Better than the 5 it was though. For those who dont know, the mighty KR1S went to a new home a little while back. The sale price paid for the last engine rebuild plus a little bit more. Good way to lose money, two strokes.