charging sys.

Yes. Recheck that you got the right vreg aftermarket for your bike. Recheck your wires for breaks, recheck all your connections. It needs to be soldered. Or you'll just keep having this issue.

The bike is basically designed to be charging all the time unless the volts are already high. If they are high, the circuit to the field coil is disconnected by grounding out to frame instead of out through the coil. To decide that, the voltage is sensed on one of the three wires going to your voltage reg on the older models, and on one of the two wires on the newer ones.

either way, it senses the voltage in the bike and decides to charge or not charge. So if you get charging bypassing your reg, then it is

a. hooked up wrong.
b. not hooked up because you used crimps or bullets which suck and can't be proven to be connected.
c. you still have a broken wire somewhere.

the good news is your charging system is fine, just your triggering is not automatic. So you can relax. You'll find the gremlin somewhere in there.

can you take a picture of how you've wired up your new aftermarket reg?
a. hooked up wrong.
b. not hooked up because you used crimps or bullets which suck and can't be proven to be connected.
c. you still have a broken wire somewhere.

a.Hook up seems simple enough, colors match, website description below in bold:(
b.Its has been soldered all along:) see pic
c. all resistance tests are passing, would this show a broken wire?
Voltage regulator for all 12 volt bikes with an electro
magnet field alternator that has one pole grounded.
If you're not sure this regulator will work for you, please ask...

This unit has short leads and a splice in harness section so you can cut it to length. Splicing supplies, heat shrink tube and
mounting hardware are come with it.

Connecting this regulator is a snap, the brown wire is positive from the main power lead. The black wire goes to ground and the
green wire goes to the field coil. I can substitute in micro plugs for use on the Yamaha two stroke twins on special order.
This is a partial list of the bikes unit will work

Yamaha: R5, DS7, RD250, RD350, XS series 650 twins.
BOOM BABY.....NAPA Part #VR38SB is also an alternate voltage regulator. Issue resolved, not sure what sparked ALL of this but I do know that my charging woes are gone, Permanently wired in the new NAPA Vreg according to the link above, used shrink tube on all connections, keep the bullet style plugs mating the the Vreg because I didnt know if solding directly to them would hurt the unit. Additionally I grounded the body with a jumper to (-) terminal and then ran the black wire from the stator to the ground bolt/batterty box mounting bolt and whammo, system is fully functional, Idles @ 1200rpm and 12.85V rev'd to 3K rpm and hit 15+ volts..NICE:D Thanks to all who contributed! On to reassemble tommorrow..Hopefully shell be raod worthy by the weeks end!
I toldja to go napa! Cheap is better than fancy.

Congrats. Can you post a photo of your wiring solution so the next guy with charging issues saves a step?

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TY gent's...I will post a photo tommorow :) I put 8 miles on her after a quick plug/points/timing tune and she runs great...I forgot about the spongy lagging clutch however.. Any who I forgot how awesome that lil bike was, I was laying into a few of my noraml 25mph bobber backroad turns at 40 and still felt this bike! Smooth as a babys ass! On the flip side I JUST discovered a problem while putting it away after 2hrs of polishing(still more to go).. I tried to start it to ride into my shed and the kick starter isnt engaging, it doest just fine when kicked slowly but once kicked rapidly it doesnt roll the engine over...related to clutch maybe? New thread coming soon unless you guys come back with an easy fix:D
The first part of the kick mates the gear to the sprocket, at which point it is nearly parallel with the ground. After that you can kick hard. If you go hard all the way, the gears may not mate properly, so the engine doesn't turn. I can't think of any other reason for it to work when you go slowly and not otherwise.
Thank you for this Thread, I have solved my charging problem. I will create a image gallery soon, and post all my extra images. Someone posted that they used a BWD Select R296 Voltage Regulator, Once I confirmed that this was the one for the 81 XS400SH I jumped at it. While I was on the O'Reillys website, I noticed that there is a set of Pigtails to go with it. Its not that I am lazy, I just don't like trying to attach things to inside prongs. What if ... It gets too hot, ... KISS One less thing for me to try to create and troubleshoot.

So with a previous order from MikesXS website , I had ordered connectors for doing the Drewpys Stator rewiring project.

BWD Select R296 $19.99
BWD Pigtail PT173 $10.99
Connector $4.50

I Crimped and soldiered (is that a word) Green to green, the Blue pigtail to the Bikes Brown, then one of the screws that I used to secure the regulator, I attached a ground wire, and included that into the wiring harness. that was Black to Black. I tried to keep it simple.:)

I had added a bigger fuse block to my bike, and the fuse block holder was able to accommodate the addition of the new Voltage reg, and conviently it was next to the bikes wire harness connector. :thumbsup: The fuse block holder is made from aluminum. so I dont know how conductive the aluminum is, so I put a ring terminal on the bolt that was holding it, to ensure good ground or earth path. so when I post the gallery pictures, The Fuse block base (bottom) I was able to drill 2 holes for the Voltage regulator (VR), which extends the VR along the plastic of the wheel well, smashing it quite snugly next to the battery box.


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Hey guys, I know this post is old but I've been reading through it as I'm having charging issues.

I wasn't getting power to my field coil(at least it wasn't magnetising.). I earthed the green wire from it and it will charge like that. This means it's my reg/rec that's the issue right?

Is there anything I can to to diagnose it further or do I just have to bin what was a new reg/rec and replace it?

Here is a fresh link, that just went over to test the field coil.

Just like it says here, find the white wires, they are all connected together. (on a 80-81) one line goes to a relay, (not part of the problem thou.)
Test all three white wires, from the rectifier to the stator assemble. (get Ohms/ and the other one, Its on the link) I bought one reg/rec and the reg side was broken, so I had to get another VR.
Generally the problem is fried wires under the back of the engine, where the white wires go up to the first white block. When you feel the wires near the rec/vr you will feel the wires are compliant, soft and flexible, but under that part of the engine, they tend to be hard, crackly, brittle. Get the book, there is screen shots in this thread for the test of the rectifier, and not much fur our VR. PS put a signature on your screen, so don't have to guess what motor your got. (control panel, to signature, put in year/type of XS, and if you have the 3 digit code, (should be on your insurance card, registration, Neck of the bike, and it should match your engine (not necessarily)