bike not charging need help

[solo]

I know this topic is getting old but I do need help. I’m good with wiring a bike and have rewired bikes before but this one is driving me crazy. Here’s the issues I’m working on a 1978 XS400 and replaced the stator and rotor and Reg/rec and still nothing. I have down loaded many wiring diagrams and notice that there are some differences. my 1st question is on the stator there are 3 white wires that connect to the rec/ref and brown to brown to power on/off, red battery, black to ground. The stator has a yellow wire should this go to a power source? The stock bike came with a separate reg and rec, so I replaced it with a 1980 rec/reg. When the bike is running the volts stay at 12.3-4 and when the lights are on it goes down to 12.2, and when I the RMP are high the volts do not go up. I connected the yellow wire that is coming from the stator to the battery and still no change to the volts. The Bike looks and run awesome, please help.

thanks solo

 

[hmusket]

I have an '81 with the same basic problem, not charging. When I picked it up, thought it would be an easy fix, regulator and or rectifier. No go. When I took the stator cover off I saw the stator was loose, and had torn wires. I replaced it with one I bought from eBay. Bike still doesn't charge. So the problem could still be a defective stator, bad regulator or bad rectifier. Anyway, that was last year, I haven't started in on the bike this year yet. When I do, I'm going to test it according to the manual in the tech section. View attachment 3882 Starting on page 23 of the pdf.

On my bike the yellow wire goes to the oil pressure switch. There are differences in your model, check out the wiring diagram on page 28 of the pdf. But the yellow doesn't go directly to the battery. Also my bike uses a separate regulator and rectifier. The combo you have may have come from a different Yamaha.

I'll be following your progress with self-interest, also if I make any breakthroughs I'll post them.

Harvey

 

[01ps]

I had a non-charging xs400 this winter. I finally traced it to the regulator, and replaced it with a 80's Dodge regulator.

I can't speak for the reg/rec combo, mine were seperate, but maybe it would be worth trying the seperate components again? I found my problem by grounding the green regulator wire and it gives you un-regulated power, ruling out basic charging issues, and isolating it to the regualtor.

 

[jigm400]

i dont know about the 78 but on my 80 the reg/rec are separate.

 

[bcware]

The reg/rec are separate on my 78 if I am identifying these parts correctly; the rect being the little box with heat sink fins and the reg being attached behind the battery box.

 

[drewpy]

yep corectomondo BC

the voltage reg, regulates how much voltage goes to the field coil, which in turn dictates how much ouput the stator makes. The AC from the stator goes to the rectifier to convert AC to DC (let there be rock!) via one way "valves" called diodes.

the separate electro-mechanical voltage regulator can be adjusted! but on the other hand it isn't quite reliable as solid state!

 

[solo]

Yes the bike had separate rec and reg, but I changed it to a rec/reg soild unit. When it had separate it still had the same problem.

 

[ahale2772]

I wish someone would do a write up on that banshee stator setup, if i knew more about mounting the actual stator i'd go for it but ive never been in there so i've no effing clue.

had for me to justify fixing a 30year old system that is very likely to fail again

 

[Drewcifer]

I've just done an after market regulator swap and get simliar symptoms. a battery that doesn't charge up or drain down really, unless I run my lights.

Did you ever solve this issue? Anyone ever solve this for him via PM?

 

[halfbreed4lyfe]

So I am having a very similar issue!!! When I have my seperate reg/rec installed, the moment i turn the key on the battery will start to drain but if the bike is running it will hit 14V. With the combo reg/rec I do not get the drain but the battery will not charge. Has anyone solved this issue yet???!

 

[BBS360]

So I am having a very similar issue!!! When I have my seperate reg/rec installed, the moment i turn the key on the battery will start to drain but if the bike is running it will hit 14V.

Within reason that's normal behavior.

With the combo reg/rec I do not get the drain but the battery will not charge. Has anyone solved this issue yet???!

Plenty of people successfully use combo regulator/rectifiers.
Which model of regulator/rectifier do you have and is the field coil properly connected?

 

[halfbreed4lyfe]

So went to xs650 site and they suggested using the VR292 voltage regulator which i went and picked up from NAPA. Switched the bike on and everything is PERFECT!!!! Started the battery on an overnight charge to get it back to 100, but it now holds just above 12 and hits 14.3 when high idle. Bikes now riding pretty nice, thanks guys.

 

[halfbreed4lyfe]

I should clarify....when I said the battery kinda drains I meant it would go from 12V to 8V in 2 seconds. I'd turn away and itd be at 3V.