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Motorcycle Repair/1999 yamaha r6


QUESTION: Hello again Lazaros I wanted to ask a follow up question but the option didn't pop up. I'm the guy with the charging issue. I replaced the rotor that was scratched. The stator reads consistent ohms, no windings touching ground. I am still getting only 11 volts ac from each. Is that really wrong because I'm not getting the full 50 volts as you said I should. At idle the battery reads 14.6vdc. At 5000 rpm it drops to 13.7
 I am really lost at this point do you have any other suggestions?

ANSWER: Hello Dean,

If you are getting only 11 volts from each phase of the alternator output, it's impossible to get 14.6 volts at the battery.

Do you take measurements with the stator wires connected or disconnected from the regulator-rectifier? Is your voltmeter/multimeter set at A/C voltage (VAC or V~ mark on the knob)?
You should DISCONNECT the connector with three white wires, and take measurements at the stator side, one tester probe to one white wire and the other tester probe to another white wire.
Continue, until each and every white wire is tested with both other wires.

As for the voltage drop at the battery when revving the engine, it's most probably due to bad connections. As I mentioned before, you should check all involving connectors for bad conductivity. Stator, regulator/rectifier, main power feed (on starter relay), fusebox, main switch (keyed) and left handlebar switch connectors. Also check ALL grounds for proper contact.

At this point, I should mention that it is very difficult for me to cope with every questioner, because all I know is the name.
I can't possibly be aware of everyone's level of knowledge. Others find my answers too hard to understand and others even get annoyed by the details, feeling I'm treating them as kindergarten-level.

So, there is no shame on asking if something isn't clear to you. After all, this page is dedicated mostly to the low-to-average knowledge biker.
Help me and let me help you...

Best Regards,

[an error occurred while processing this directive]---------- FOLLOW-UP ----------

QUESTION: Sir you were absolutely right. I wasn't getting enough connection with my meter leads. I disconnected the harness and got 55vac on all of them so I guess the rotor may have done the job just one last question. At the battery is 14.5@ idle and 13.7 @ 5000 rpm ok? If it is then problem solved. Thank you

Hi Dean,

As for the rotor-stator part of the problem, problem solved.

But, charging voltage at the battery should be more than 14.2V at all times.

You have to check all connectors for corrosion and/or oily residue and clean them thoroughly.

Pay special attention to the main switch.

Best Regards,

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Lazaros Ampatzidis


I can help you on EVERY issue involving POST-1980 Japanese Motorcycles plus KTM and Husaberg. My field of expertise includes Engine, Transmission, Fuel system (carburation & EFI),Electrics and Electronics. Maintenance, repair and tuning. Road and off-road suspension tuning. Please don't ask me about non-Japanese Motorcycle, especially American built on which I have low to zero experience.


I'm a rider and hobbyist since childhood. 25 years motorcycle workshop mechanic.15 years motorcycle racing mechanic. In order of experience high to low:Kawasaki,Suzuki,Honda,Yamaha,KTM,Husaberg.

Hellenic (Greek) Technical School.Internal Combustion Engines Engineer. Automotive Electronics.

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