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Charging system failure??

Freightdog

CB750 Member
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Location
Purling, NY
Yesterday I pulled into a rest stop and shut the bike off. When I attempted to start it again, the battery was dead. After push starting, I got to the next exit and noticed that my turn signals no longer worked. I chose to shut down and have the bike towed home. Removal and inspection of the battery found it almost dry with staining from the acid boiling over. Cleaned, re-filled, and charged the battery and it seems to be holding a charge. Ran the bike with a volt meter across the battery. Volts at the battery began at 12 volts at idle and dropped to 9 volts by 5000 RPM. I have not checked the stator output yet. Removal and inspection of the stator found one section of the stator ring worn down to shiny bare metal as if the rotor is making contact with it at that one point as it spins. Can't see how that is possible though. Any suggestions on a diagnosis or how to proceed? I had suspected an overcharging situation but obviously I was wrong.
 
Closer inspection shows definite wearing in one area on the stator and small metal flakes are visible inside the cover. There is no visible adjustment on the stator and the rotor is on the crankshaft. ????
 
So... Clearly the rotor is making contact with the stator at one specific point. This has caused both the rotor and the stator to be worn down and it's safe to assume this was the cause of my charging failure. Thankfully, parts are still available and easy enough to replace. The problem is that the rotor mounts to the crankshaft in only one specific way. The stator mounts to the cover with three screws in one specific, non-adjustable way. The stator/cover/gasket mounts to the bike in one specific way. Why are they rubbing and how do I prevent the new parts from doing the same?
 
One suggestion I heard was a bent crankshaft. How would the crankshaft end up bent in the first place and what would the symptoms be?
 
Its possible the previous owner had tried to remove the rotor with the incorrect puller and/or a hammer was used to try to jar it loose. (I have seen people try it) You need to set up a dial indicator and check how much runout you have. Is the rotor worn in one spot or all the way around? A bent or out of round rotor would be worn in one spot. If the rotor is worn all the way around then the stator is not centered in the cover or the cover is not aligned to the cases properly.
 
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