Following up from the “Very Long List” post. First task was take out the engine and gearbox, my favorite pass time!
The problem with the starter motor not engaging correctly quickly showed up when I tested it on the bench. The pinion gear wasn’t engaging fully, see the first video.
What should happen is this:
For those not familiar with the starter motor on an Aprilia it is a Marelli MCE 0.4/6R, mine is six volts, and is activated by pulling a lever under the dashboard then via a cable to another lever on the starter, none of those complicated electronic solenoids to fail, as long as the cable doesn’t break they are super reliable!
A close inspection and comparison with my spare unit reveled the cause of the problem. Someone in the past, not me, had soldered a copper button on to the contact unit and welded an extra bit onto the actuating lever, see the comparison with the spare motor. Simply put this didn’t allow the pinon gear to travel its full length and engage the ring gear correctly or sometimes not at all.
A simple job to remove the extra button, grind off the extra weld and I now have two working starter motors.