I have a 2002 Ducati 748S with 40,000 miles, that I've owned for about 6 years now. In the last year or so the bike has developed a very bad surging/undulation that I assume is a misfire. I am the second owner of the bike and it has always been serviced on time, also by the the previous owner of the bike who gave me all of the old service records. Sadly the bike has been dropped twice (at low speed, ~15mph, by me) _after_ the issues developed, so I don't thinking the accidents left any serious damage. The misfire is present at all RPMs, yet does not cause long cranks, stalling, or back firing of any kind. The bike is almost ironically 100% reliable. The "misfire events" increase with RPM but do not cause the engine to break up. I ride the bike a few times a week to work, to keep it from sitting, so it always has fresh gas and oil changes.
What my mechanic and I have tried over the last year:
*Cold compression test: 149PSI rear, 145PSI front (did this today)
*Verified the woodruff key on the layshaft did not shear
*Swapped ECU with a similar bike (using same EPROM)
*Swapped tank and pump with a similar bike
*Swapped throttle bodies and injectors with a similar bike
*Replaced the wiring harness with a low mileage used harness
*Replace the CPS with a new unit
*Verified CPS gap
*RPM drop test, vertical cylinder is potentially low contribution? When unplugging the coils, the rear cylinder makes less of a difference in RPM when unplugged.
I can get pictures of the spark plugs if anyone is interested. I can also get audio/video of the bike, I believe the "misfire" is very audible, the bike just doesn't sound right.
Everyone who has worked on the bike is at total loss at this point. Obviously a lot of parts were temporarily substituted yet did not yield a positive change, so I am starting to wonder if it is a compound issue, or if some of the tests should be attempted again. Unfortunately I don't have another Desmo but I might be able to get parts to swap. Any input/direction/ideas/comments/thoughts are more than welcome!
Thanks in advance