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Headlights Dim with Throttle


SFD213

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I’ve been working to get my brother’s 99 up to par since we purchased it a few months ago. When the bike idles, the headlight works relatively well. Once the bike raises above idle, the light dims. Alright, so let’s check the battery. Battery is meh but not bad. Throw it on the charger for a few hours, let it sit a few hours after that and recheck. Battery still isn’t the greatest but it’s not to the point of replacement. Okay, I’ll swap my battery (from a 6th gen) with his and check. Same thing. Maybe my battery is shot too? Reinstall in my bike, twist throttle, light brightens. Okay so not the battery. Check the stator (stock), stator checks out and has ample and equal output across the three wires. Alright. Now I’m scratching my head and clutching at straws. I wire wheel the terminals and connections with my dremel and wire wheel the bolts. Nope, wasn’t a bad connection. I’m lost. Bike runs like a champ, maybe a little toasty, but it’s a vfr. Anyone have any idea?

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Also, it’s not a first post without a picture of the bike. Well that’s both, and they’re both in pieces there, but it’s a picture nonetheless. Don’t mind that jack wagon in the back

D6C5702F-32D2-4A40-AB72-B6F2699E6A03.jpeg

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Given the battery looks OK and the stator checks out, that leaves the RR which converts the AC to 12V DC. Put a voltmeter across the battery terminals and check the voltage while idling and at say 5000rpm. Should be 13.5 -14.5V, but a failing RR will affect that, either higher or lower. 

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Given the battery looks OK and the stator checks out, that leaves the RR which converts the AC to 12V DC. Put a voltmeter across the battery terminals and check the voltage while idling and at say 5000rpm. Should be 13.5 -14.5V, but a failing RR will affect that, either higher or lower. 

Thanks I’ll check it out


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You might also check out the common earth block on the harness. I'm a 5G guy but I believe a 6G has a pale blue rectangular block under the tape cover on the harness under the front cowl. Corrosion here is not uncommon and leads to odd electrical problems unrelated to the charging circuit. 

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You might also check out the common earth block on the harness. I'm a 5G guy but I believe a 6G has a pale blue rectangular block under the tape cover on the harness under the front cowl. Corrosion here is not uncommon and leads to odd electrical problems unrelated to the charging circuit. 

It’s a 5g that has the issue. I was just stating that I used a battery from my 6g as a test of the battery. You know where the common ground is on the 5g?


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IIRC left side under the tail cowl, again it is part of the loom so covered by tape. Feel for a rectangular block about 1" x 3/4" x 3/8".

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Given the battery looks OK and the stator checks out, that leaves the RR which converts the AC to 12V DC. Put a voltmeter across the battery terminals and check the voltage while idling and at say 5000rpm. Should be 13.5 -14.5V, but a failing RR will affect that, either higher or lower. 

Checked it. Ran 13.5-13.7
IIRC left side under the tail cowl, again it is part of the loom so covered by tape. Feel for a rectangular block about 1" x 3/4" x 3/8".

All clean and no corrosion. Looks like it came from the factory.

I’m genuinely stumped by this


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4 hours ago, SFD213 said:


Might just be Tapatalk but all those posts say the content is unavailable and that everything was posted on 12/31/1969 lol

Thanks for the heads up... This is the charging system check out procedure - yeah it is a couple years old.... Got a multimeter? If not, go grab one. 

Well gang, since they did it on the other side of the fence (VFRW), I thought I may as well post the Drill here solo too. Plenty of guys have used this to find out what the hooey is going on with their non working charging system.....  

 

"The Drill"

 

Sorry for your electrical troubles. Well, looks like you gotta do…. “The Drill.”

Go through all your connectors for burnt leads, dig deep. Crispy wires? Not good. Your gonna have to fix that!  

Then---Go through this starting point quick list.  You will need a multimeter too.

Steps:

- Recharge battery overnite - then to take it to Autozone, Batterys Plus or similar to load test. -- Good? Bad? – An iffy battery can fake you out and act like a bad R/R. Buy new if needed. -- A GOOD BATTERY IS THE FIRST THING!

- With good battery fire it up, warm up for a minute or two.

These are R/R quick checks---

--- With voltmeter at battery get voltages -- idle volts? 5000 rpm volts? What’s the numbers? Should be in 13ish min idle and in 14s at revs. If in the 12s at idle, try at 1900 rpm. (It’s not unusual for the system to be in discharge or no charge at idle.)

- Check stator

- 1. Pull connector apart. Set meter to resistance. Check pin to pin stator side, 3 yellow wires, A to B, B to C, C to A. What’s the numbers? 3 separate readings --Should be less than 1.0 ohms.  (Engine off)

- 2. Check continuity from each A,B,C pin stator side to ground, -- -should be infinity - nada nothing. no continuity.  --   3 separate checks. (Engine off, again connector is apart)  -- Again, what's the numbers? 

- 3. Crank it back up. Do another pin to pin thing, but set meter on AC volts. idle and 5000 rpms. What's da numbers? Should start 15 -20ish and climb 50ish and more.  Again – 3 readings stator side connector and still apart.

- Repeat hot if you dont find anything wrong. Sometimes the stator will be fine cold and be a problem hot. 

(If you find the probem cold, you dont have to redo this hot)

 

This quick list will catch the obvious stuff, but if you need to dig deeper check this chart. (Some guys like this chart, my taste, I don’t care for it.)

http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

 

Cheers and beers gang....

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