'81 XS400 Doesn't Want to Charge

[fR3ZNO]

I don't mean to be "that guy" right now, but after reading a few threads with no definitive answer, I felt it was okay to post my own question/thread.

An XS400 with charging problems is almost cliche... lol

Anyways, here we go, story time.

I got this bike a few months ago now, and it would die unless it was hooked up to the battery charger. Okay, no problem. Bought a new battery and could ride the bike for awhile, but it would not charge (big surprise, there).

So I did the test listed in the manual, tested the stator wires, resistance between the three of them were consistent and were at 1.1 ohm. Tested the rectifier and regulator, diodes in rectifier tested to be not good, regulator was okay.

Decided to buy a new aftermarket component. But I was stupid and bought one for a XS650. ESR350

I emailed their customer support and the guy said that it should work with my bike even the regulator plug is missing a black wire and that they all run off of a common ground now that is the black wire in the rectifier plug now.

So I wired it all up, using the original connector from my rectifier.

Along with the info listed here on this site, I also used this flow chart (see attached) from the same company that sells the RR.

With the bike running and at around 3k-5k rpm, the voltage at the battery is still roughly 12.5v. So, not charging. I measured the AC volts of the three white wires coming out of the stator (with bike running) and got around 16 volts, I believe. I remember that it was well below the 50v or so required.

I also, measured the resistance from the engine case to each of the stator wires and got around 4.5MOhms, essentially infinite resistance.

Following the flowchart, I connected the black MM lead to the positive battery terminal and red MM lead to the red output wire on the RR. I got a value of .5V, which according to the flowchart says there's a bad connection in the positive lead from RR to battery. I did the next test which is the reverse of the previous, red MM lead to negative battery terminal and black MM lead to black output of RR. I got 0.1v which is supposed to be ideal (less than 0.2v).

I stopped there for the most part. Did some other tests on the flowchart and since the AC volts coming out of the stator were lower than 50v, it says the stator is at fault. Which makes me think maybe the wires are worn through like they usually are?

I still have to pull the stator cover and check the wires for breakage, but I thought the resistance check would be sufficient.

Jeez, sorry for the novel. Just would like to fix this thing and get some riding in before the snow starts flying... lol

Not really sure where to go from here... any help is appreciated.

 

[DARKMIDKNIGHTWARRIOR]

Wish I could help.

 

[arfstrom]

As you have seen, I have promoted the Drewpies re-wire, Look at picture 4, in this pic, the frayed wires that you see there, are under the drive sprocket, droping under the engine, and up the back side. if you touch those wires, they are probably toast. you know krispy, crackly, The rest of the wire is probably fine, but we recommend to do the stator rewire, like in this post. Then as long as you in there, do all 5 of them. since you have to take it all out anyways.

Mind you, I have no idea what bike you got, we strongly recommend you to click on Control panel, and add a signature, so you don't have to tell everyone what your working on. (also some of us are not young, and have short term memory) (I could be wrong)

http://www.xs400.com/forum/showthread.php?t=5934

 

[fR3ZNO]

As you have seen, I have promoted the Drewpies re-wire, Look at picture 4, in this pic, the frayed wires that you see there, are under the drive sprocket, droping under the engine, and up the back side. if you touch those wires, they are probably toast. you know krispy, crackly, The rest of the wire is probably fine, but we recommend to do the stator rewire, like in this post. Then as long as you in there, do all 5 of them. since you have to take it all out anyways.

Mind you, I have no idea what bike you got, we strongly recommend you to click on Control panel, and add a signature, so you don't have to tell everyone what your working on. (also some of us are not young, and have short term memory) (I could be wrong)

http://www.xs400.com/forum/showthread.php?t=5934

Yeah, I was planning on pulling the stator and doing a rewire. Damn thing probably needs it anyway. Just wanted to avoid it. Haha. Sort of assumed that since the resistance values for the stator were consistent, it was okay. I got around 1.1 ohms for the three of them. I believe that's out of spec, but the flow chart says that's acceptable.

Not to be a dick, but I list the bike in the thread title. Not sure if that's specific enough for you.

I have a 1981 XS400 Special. I'll add it to my signature for future posts.

 

[arfstrom]

Remember, rewire, is just replacesing the last 2 feet of wire or so, not a stator re-wind. The last guy I remember helping, went and did a re-wind for $100, and I think he is still down.

Like the 5 or 6 pic shows, your just make your connection inside the stator housing. (I am also recommending a quick coat of enamel spray paint, just to help with the isolating the wires from the oil bath. (mine the heat shrink didn't get as tight as it could, so this time I sprayed painted with enamel, before heatshrinking.

 

[fR3ZNO]

Remember, rewire, is just replacesing the last 2 feet of wire or so, not a stator re-wind. The last guy I remember helping, went and did a re-wind for $100, and I think he is still down.

Like the 5 or 6 pic shows, your just make your connection inside the stator housing. (I am also recommending a quick coat of enamel spray paint, just to help with the isolating the wires from the oil bath. (mine the heat shrink didn't get as tight as it could, so this time I sprayed painted with enamel, before heatshrinking.

Yeah, I'm hoping the wiring is the only thing that needs to be replaced. I don't really feel like spending that much on this bike right now. (poor college kid status lol)

I think if possible, it would be best to find some UL Recognized wire that's resistant to oil. Not sure where I would get some in a small amount, though.

 

[Wolfe_11B]

Standard automotive wire is resistant to pretty much everything-
http://www.wirebarn.com/GXL-Automotive-Wire-by-the-Foot_c_29.html

 

[mattg666]

Ok, this is a good start for the rewording part. But I'm just curious... Is there any place that sells just a new stator and rotor for the xs400?? I have a 1980 with tci ignition... And of course. The charging system sucks... And I don't want to just keep replacing the used bad stuff wih more used bad parts that will only last a few months.... So if anybody knows of one that will work for the 400, that would be awesome!

 

[Wolfe_11B]

Is your stator and rotor broken? They really don't break often. Most issues I've seen are caused by all around bad wiring, bad regulators and rectifiers, ect.

But to answer your question, no, there are no direct replacements.

 

[mattg666]

Reg and rectifier are brand new. Wiring has been redone. But not inside the stator/rotor... Which yes is highly probable... But still, if I'm breaking it open and rewiring I'd like to go ahead and put new components in it... Which brings me back to my question, do they make new ones or any that would be compatible with a tci ignition?

 

[fR3ZNO]

I don't think there are any companies that make direct replacements for the XS400. There are some that I have heard will rewind the stator for you.

Only other thing I could think of would be to retrofit a newer bikes stator and rotor, but I feel that would be difficult to do.

 

[fR3ZNO]

Okay, giving my thread a bit of a necro bump after I was able to get to do some more diagnosing on by bike. I am unable to get voltage from the plug that the regulator goes into. So my understanding is, that if the regulator is not getting power then it will be unable to energize the field coil? The wires on the stator and coil look good. I took them out yesterday, and the resistances checked out. So where do I go from here?

 

[arfstrom]

Okay, giving my thread a bit of a necro bump after I was able to get to do some more diagnosing on by bike. I am unable to get voltage from the plug that the regulator goes into. So my understanding is, that if the regulator is not getting power then it will be unable to energize the field coil? The wires on the stator and coil look good. I took them out yesterday, and the resistances checked out. So where do I go from here?

http://www.xs400.com/forum/showthread.php?t=13139 4 pages of info.

Have you gone through that post? Plug, is that plug oem to the regulator? That is another good thread to go though.
http://xs400.com/forum/showpost.php?p=88162&postcount=72
You can see in that post there is a specific pigtail to go with the VR.

s, that if the regulator is not getting power then it will be unable to energize the field coil? The wires on the stator and coil look good.

So like I was explaining in the first thread (13139) somewhere in the first page,
1 bike is off, energy contained by key/battery.
2 key is on, battery energizes everything (but headlight)
3 Bike starts (kick/e-start) stator energizes White wires
4 white wires sends electricity to rectifier/diode to headlight relay (headlight on now)
5 rectifier send electricity to wire harness, the Voltage regulator monitors electricity level.
6 Voltage under 12.5 VR turns on magnet in Stator (energizes stator via field coil) (on or off if over 13.5 or so)

So my thought is that either your plug isn't working or your VR is dead.

Remember the statement about the regulator being mechanical is for the bikes earlier than 80, idk.

So I suppose the last thing to check, is every ground. Freshen up every connector. take a piece of sandpaper, and rub it in every connector, and grounds. Under the seat to the left of the batter, the Neg to the engine, turn signals have a ground too.

 

[fR3ZNO]

Thanks for the response!! I'll take a look through this detailed answer and report back soon.

 

[fR3ZNO]

Okay. Not sure if that was posted in the thread before, but I have a new reg/rec (single unit) installed and the plug that goes from the regulator has two wires instead of the original three. The new unit uses just a green and brown, no black. I spoke with the company that makes the unit (it's made for a 650, but I figured it should work for my bike) and they said that the unit uses the black ground wire in the rectifier plug. So I don't believe that should be causing an issue, should it?

 

[arfstrom]

I believe that is what I ended up doing with my system.
I had blown out the VR portion apparently when I attached mine. I had the ACCEL model, and I did call the manufacture, They said it should be fine. Since then that model is impossible to find again. End result I have a VR from Oriellies, with a pigtail.

I guess I would make sure you have a good ground on the unit, just to make sure.

http://xs400.com/forum/picture.php?albumid=342&pictureid=2368

 

[fR3ZNO]

So, my dad was tinkering with the bike for a bit tonight and got the bike charging. Guess what was wrong with it. The voltage regulator brown wire was supposed to go to the black wire on the plug (bike side)... It's now charging at around 15V.

Also rewired the stator wires.

 

[fR3ZNO]

Off topic, but how loud is the valvetrain typically on these bikes? When it's running there's pretty loud valve tick.

 

[TimBuz]

Good to hear you got it charging! Ive been stressing about mine not charging, but i think i need to recheck the wiring for my reg/rec too.

 

[fR3ZNO]

Yeah I am super psyched that i can finally ride it without the battery dying haha