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Registered Badass
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Discussion Starter #1
There's gotta be gremlins in there! It's one of those days where I just want to part the thing out and be done with it. But my desire to ride keeps me pushing on.

Anyway, I put the key in the On position, put her in heutral, grab the clutch, press start and... I hear a single click of the starter relay and then nothing. All the lights go out and the voltage at the battery droms from 12.6 to 2 volts. It stays that way for about 10 seconds and then like magic, it jumps up to 12.6 again as if nothing ever happened. All the lights come back on and if I want to torture myself again I can press start and repeat the process.

A lil history can be found in this thread (http://www.vn750.com/forum/showthread.php?t=20398) but I'll summarize it here:

The stator is bad. I've been using a charger to maintain the battery but for the past couple of weeks both the charger and R/R have been disconnected and the bike hasn't ran.

The R/R was replaced a month ago with a MOSFET but aside from running the bike once in the driveway it has not been used.

The junction box was replaced a day or two before the R/R was replaced.

The battery is a MF Yuasa but it's few years old and probably been through hell while I troubleshooted the charging system.
 

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Did all these type problems start after you did all this maintenance?

You replaced your junction box with one from a ninja 600? Are you sure there compatable? Im also curious how you did the wiring for your Mosfet R/R.

The bike should start and run fine with the R/R disconnected as long as the battery is good, but as soon as the battery gets low enough not to support the ignition, it will stall. The stator and R/R is just for keeping the battery charged. so if your having this problem with it disconnected, you know thats not where the problem is.
 

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Registered Badass
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Discussion Starter #3
The junction box from the ninja is the same part in our bikes. I did swap it out with the original to rule it out and had the same issue. The ninja box worked fine when I originally put it in.

As you said, with a charged battery and the R/R disconnected, the bike should run assuming the battery's handling the load (which I suspect it is not). I don't want to run out and buy another battery without some second opinions though.
 

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Chucklehead
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Double check connections for corrosion/tightness. Another left field possibility could be the stater brushes, not hard to check but it calls for pulling the starter which calls for draining the oil. A quick check is using jumper cables connected to a car battery (non-started vehicle) If these check out then the culprit is the battery, but I'm more inclined to think connections.
 

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That also happens when you have a short sometimes.
 

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HAWK
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Sounds like a loose or bad ground, try running a new thick wire for a grount to eliminate a posibility.
Had the same issue on a car a couple of months ago.
 

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Discussion Starter #10
Thanks for the suggestions. Seems like the ground wire is ok. I had to leave the key in the On position for a few minutes this time before I got any voltage to show at the battery. Then like before the moment I pressed start it dropped to .5 volts. I waited about two minutes for it to come back up again before cleaning up my tools and calling it a night.

@Knife
I do in fact have a bell. However, it is one I bought so as you know, it's power is reduced. That bell is a replacement for one that was given to me though. The original was bitten off by a road gator that I hit at 90mph in the Nevada desert. Sometimes I wonder if it would have taken my foot had the bell not been there ;)
 

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Discussion Starter #11
Just following up. It was the battery.
Once I replaced the battery everything started acting as expected.
 

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The battery dropping to ~2 volts sounds like it might be a ground issue.
 

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I think I would check the voltage at the battery with the bike running at 3K rpm. I would want to make sure that the charging system wasn't trying to overcharge the battery or charge to rapidly. The voltage should stay at or under approx. 15 Vdc. Much over, and you might be shortening the life of the battery.
 

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Discussion Starter #14
Z that's a good suggestion. I'm going to give it her first good run tomorrow. I've got one of those LCD volt meters on the handle bars so I'll pay close attention to that. I would hope that the fancy pants MOSFET R/R I just put in would limit the voltage but it's a valid concern to watch for.
 
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