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Discussion Starter · #1 ·
So I have a 2002 Yamaha YZF-R6 and it is not starting. When I put the ignition to "on" and the kill switch is "on", all the lights are bright and normal. Once I flip the kill switch to "off", the lights dim drastically. I try to start it and it just buzz under the seat.

I connected it to my car with my jumper cables and it started perfectly. I leave it running for couple of mins and everything seems fine. However, while it is running and I rev the engine, the lights and the speedometer dims then turn off, but the engine is still running. Then when I stop reving, and everything turns back on and the engine is still running fine.

I turn it off and try to start it without my car, and the problem is still there.

I replaced the battery three times and the results are the same as before, so it is not the battery. I checked all the fuses and they are all not blown.

Can someone please assist me with this issue and how to fix it?
 

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You have a whole bunch of power going somewhere! There are only a few things that can eat enough power to dim your headlight. Starter motor and the fuel pump, followed by the headlight, horn and radiator fan. Those are your high energy consumers.

Does your horn work good all the time?
 

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While a charging problem is possible, I would check very closely for a loose ground.
That would fit the symptoms, lots of people forget to check the ground cable.
 

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That would fit the symptoms, lots of people forget to check the ground cable.
:unsure: Battery ground is the first thing to check, it's the first thing to corrode, you can spot the negative battery terminal by all the corrosion on it. If the copper on a ground connection has become hot from resistance, it will appear more black in colour instead of bright copper and you should replace it.
Same holds for any other battery equipped machinery unless it has positive ground.
 

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You don't have a bunch of power going somewhere if it never was there to begin with. Battery needs measuring with key off and then with key on to see if the power drops like a rock. Also again measure battery with engine running.

A ground problem is the ABSENCE of power going somewhere.

Measure the battery with a voltmeter.
 

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Discussion Starter · #9 ·
Thank you for you all for the the reply so quickly!

So I checked the charging system and found out that the problem is that my battery isn't increasing voltage when its running and reving. I checked the ohms on the stator, all read 0.9 ohms. I checked the AC voltage of the bike in idle and all read around 16v. When I rev the engine, it all reads around 50v. (Correct me if i am wrong for this one) I check to see of the stator is ground by checking the ohms of the one of the stator prong and the black part of the multimeter to the negatives side of the battery. The reading was 1 (or I). So the stator is good.

I checked the ohms on the regulator and it read 520ish. Is there something else that would prevent the stator volts from reaching the battery to increase the voltage while it is idling and reving?
 

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The regulator, you can't measure it that easily as there are a lot of parts inside it and the only way to really know is replacing with a known good (new) regulator.
 

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I check to see of the stator is ground by checking the ohms of the one of the stator prong and the black part of the multimeter to the negatives side of the battery. The reading was 1 (or I). So the stator is good.
Having trouble understanding. Are you saying your stator IS going to ground?
A good stator does not go to ground at all. When testing to ground you want your meter to read infinite.

I checked the ohms on the regulator and it read 520ish. Is there something else that would prevent the stator volts from reaching the battery to increase the voltage while it is idling and reving?
Yes... Bad wiring, corroded plugs and such will do it.

There is a way to test the rec/reg but it is possible that it could test good but still be bad. If testing shows it to be bad then it is bad.
I can dig up my notes on rec/reg testing if the stator verifies good. In my experience stators go bad much more often than rec/reg's.

S F
 

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Discussion Starter · #12 ·
Having trouble understanding. Are you saying your stator IS going to ground?
A good stator does not go to ground at all. When testing to ground you want your meter to read infinite.


Yes... Bad wiring, corroded plugs and such will do it.

There is a way to test the rec/reg but it is possible that it could test good but still be bad. If testing shows it to be bad then it is bad.
I can dig up my notes on rec/reg testing if the stator verifies good. In my experience stators go bad much more often than rec/reg's.

S F
Sorry, you are right about the stator, I was not explaining the stator part correct. And I tested the regulator, and it seems fine. But I see what you are saying that it could still be bad even if its good.

But if you want to share your notes, that would be greatly appreciated!
 

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Discussion Starter · #13 ·
The regulator, you can't measure it that easily as there are a lot of parts inside it and the only way to really know is replacing with a known good (new) regulator.
I got a good regulator today so I will put it in tomorrow and see the result. Is there anything I have to do to the regulator or can I just unplug the old one and plug in the new one
 

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Plug it in and see. Make SURE the battery is FULLY charged as parts often fail trying to fill an empty battery now with how much the alts can put out.

Lots has been written about how to check regulators but the big OEMs commonly use a new regulator as a test part now as there are simply 50 ways a reg can fail and some will pass any test called for yet not work right. If one with the diodes (rectifier) inside it then you can't possibly check those as the result can be wrong unless all of them are broken apart, the good reading simply bypasses the bad diode to go through a good one and a complete miss of a bad part.
 

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But if you want to share your notes, that would be greatly appreciated!
I got a good regulator today so I will put it in tomorrow and see the result. Is there anything I have to do to the regulator or can I just unplug the old one and plug in the new one
Replacing a possibly bad rec/reg with a new one is a sure fire cure (and THE test) for a bad one so... Let us know.

S F
 

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Discussion Starter · #16 ·
Replacing the regulator fixed the issue! That is crazy, even though I tested the old one and the results were good, it still ended up being faulty.

I appreciate you all for assisting me with this process!!!
 
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