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Old 08-09-2012, 09:23 AM   #17
jconly OP
Gnarly Adventurer
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Joined: Aug 2009
Location: NYC
Oddometer: 426
Originally Posted by GoNOW View Post
With the new info, it sure sounds to me like you have a problem.

I would bypass the fan switch and force the fan on and turn anything else on to create as much of an load as possible. Then hold the engine at 4,000 RPM or so to simulate running down the road. Then check for voltage drop across all the connectors dealing with the charging system. Also check battery voltage with a DVOM and compare with your meter.
So, with a full load, fan running and all... voltage at the battery reads 14.1V now. When I bring it up to speed, I still get the drop to around 13.5V or so. This feels a little bit better. Not sure what changed to be honest. Cleaned some connectors.

So anyway, I figured I'd check voltage coming straight from the VR as well under these circumstances. Left the ground on the battery, and took the + reading right from where the + DC connects from the VR to the wiring harness. I'm getting a reading of 14.25 --> 14.3 V there. Hmmm. Resistance in the system just nocking down the V @ the battery?

Originally Posted by GoNOW View Post
Also check AC voltage on each leg of the stator (especially if you start seeing the low voltage problem). It does not happen often, but a shorted stator can be just fine at idle, but voltage will drop at higher RPMs and/or when it's hot. Check both with no load (regulator unplugged) and under load.

Most of the time when a 3 phase stator starts to die, only a single phase goes, so if you compare the 3 and see one that has lower voltage, then you found your problem.
Checked this yesterday as I mentioned. Everything came back equal and fine, around 65VAC on each leg, around 5000 RPM. Seems normal.

Originally Posted by GoNOW View Post
I am placing more bets on a bad connection. That brown connection is known for having problems.
I hope you're right, but I sure as hell cant find it. I've disconnected and cleaned almost everything, with the exception of some of those really hard to get to ground spots on the engine. Unfortunately, that means the battery ground.

I did pick up a 11.2 AH battery this morning to test ,to see if this makes a difference.... But when I took measurements of the 8AH that was installed in the bike this morning, it was sitting happily at 12.95V. Had it tested at Batteries Plus when I got the new one, and it was testing somewhere around 230 CCA (Rated 180). Used it to start the bike to do these tests just now, and the lowest drop it saw was down to 10V. Better than the 9 yesterday..

Well, I guess I'll try the larger battery now to see what happens.
Will also let the bike run for a good while too to test the stator again once it's up to temperature.
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