Aftermarket Regulator/Rectifier install

mcrowell75

XS400 Enthusiast
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Hi, I've been away for a bit. Some of you may have seen my you tube video for setting the timing that I made a few years ago.

I bought another xs400 last year after a brief and stormy relationship with a Harley. Never again.

My battery box was nasty because of a leaky battery somewhere in its history. I pulled it out and I in the process of removing the Rectifier from the corroded battery box, I damaged it.
IMG_3221.jpg


Its tough to see here but I was trying to drill out the mounting screw and I drilled into the body of the rectifier.

For reference here is a picture of the regulator, It should still be good. The bike was running well before I put it away for the winter.
IMG_3223.jpg


I've decided that I'm going to replace the originals with the notorious chinese combo units that go for about $21-$25 on ebay/amazon. The product listing clearly states it will work on a 1978 xs400. LOL.
71rDK7uzZuL._AC_SL1500_.jpg


Before you send me hate, I have searched the forums here and seen plenty of folks asking about these. I cant seem to find any info anyone who actually installed one.

Obviously I will need to cut and splice the old plugs onto the new combo unit.

I understand these are "chinese" and possibly unreliable. I'm doing this for the good of the forum and science in general.

I will post pictures of my progress and any multimeter readings you guys request.
 
I have hit my first snag. After looking at the Chinese combo unit again, I noticed It does not claim to be compatible with a ‘78 xs400. It only claims to work on ‘82 and ‘83. Those are Years that Yamaha used a combo reg/rec unit as stock in the xs400.

I’m beginning to think that separate rectifier and regulator options are my only hope.


There are options that claim to be correct such as this one.
IMG_3226.jpeg


This one goes for $40. That’s as cheap as I can find. There are some others that go for around $100. They are not easy to find. Notice the two separate plugs. The one that matches the original regulator plug is missing the black ground wire. This concerns me. In trying to decipher old threads about these things. I think that missing ground wire is an important issue. I could be wrong though.

I’m going to call this experiment a no go. For now. For these reasons.

1. Exceeded cost.

2. The potential for killing my battery/starting a fire is too high. See #1.

In summary, I believe that in 2025 there are still no safe, economical, plug and play solutions for rectifier/regulator combo units in older xs400 motorcycles.
 
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