I could use some advice from those more experienced with Miarellis than I am. I have a Concord XKe that I'm fixing up for a roommate, and it has a disturbing high speed clatter. The one and only obvious problem of the engine is that someone in the past dumped the bike, hard. This resulted in severly bent pedal arms, pedal shaft, and breaking off a piece of the case, in a four square inch area around the left side pedal shaft exit hole. The broken case piece was JB welded back on, and leaks oil when running.
Other than that, it seems fine. Starts, idles well, goes about 30. Except at around 22MPH, the engine develops a loud clattering noise, in time with the engine speed. I believed it had something to do with the top end, but upon tear down I found everything satisfactory. Both rings unbroken and not worn excessivly, intact piston, not hitting the head, smooth bore, adequate crank, good bearings, no play or noise, correct timing, etc.
Any guesses? Could the bent shaft be causing a problem? Should I just run it until is explodes, and then rebuild it, or rebuild it now? I'm willing to split the case and replace the internal components with new bearings and seals, but it would delay the project and add cost.