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-   -   1090RR intermittent-start problem & resolution (https://www.mvagusta.net/forum/20-maintenance-tech-issues-all-4-cyl-models/241911-1090rr-intermittent-start-problem-resolution.html)

racasey 04-23-2019 09:54 AM

1090RR intermittent-start problem & resolution
 
3 Attachment(s)
My 2010 1090RR with 25K miles developed an intermittent start problem. On two occasions, it failed to re-start when I stopped for fuel. If allowed 20 minutes to cool, it started without effort. As I had already replaced the starter relay, soldered all crimped cables, including the battery ground to frame, battery to solenoid, solenoid to starter, I suspected the starter.

On the second occasion, once started, I rode home, shut off the bike, and attempted a restart. Zero... no start. I could feel the start relay latch and with a VOM meter could read voltage at both sides of the solenoid, I was confident the starter motor was indicating an "open" condition. Power off and sure e’nuff, the circuit between the solenoid and motor read open.

With motor removed and opened up for inspection, the problem was obvious. Two brushes carry +12V to the commutator. The other two brushes must satisfy the “ground” connection or the motor will not energize. The ground brushes are easily identified. Both ground brush woven copper leads terminate in a ring terminal which are secured to a plastic ring which makes up the brush holder. A Phillips head M5 screw secures the terminal to the motor body and provided the necessary ground path. Looking at the ring terminal under the head of the screw I could see that plastic had partially melted and deformed resulting in poor contact between the ring terminal and the M5 screw. This burnt and faulty connection fails to provide a solid ground path for the +12V going into the motor.

Both M5 screws were removed, the ring terminal and screws cleaned, screws replaced and secured with 222 Loctite. And to add some redundancy, an electrical solder bridge was built up between the brush copper ring terminals and the M5 screws. I like “belts and braces”. With dielectric grease applied, the motor was reassembled, the bike returned to service. Since I've gotten 8 years and 25K miles service so far... I hoping that I'll get similar time and distance on this repair and maybe longer...

Ciao,
Dick Casey

silentservice703 04-23-2019 10:20 AM

Nicely done...and thanks for the write up and pictures!


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