New Solid State Regulator/Rect from Mike's XS Not Regulating. '75 XS650B

[Banzaibob]

1975 XS650B with a 750cc kit. When it runs, it runs great. However the stock charging system has always been sketchy. Did some voltage readings and found that it wasn't really charging well until it was revving well over 4000rpm. I was going to try and troubleshoot the stock setup but instead decided to opt out for a solid state unit specifically for the '70-'79 with breaker points, part# 24-2089.

The wiring off the new unit consists of: 3 white stator wires, red battery, black ground, green and brown field coil. The stock setup from the wiring harness has the 3 stator wires, red and black wires on one plug that goes to the stock rectifier. The plug to the stock regulator (green, brown and black) is situated to the left rear top of the battery box. I found that the black ground wire leading to the rectifier had a short and most of the insulation was burned away. I opened the wiring harness and replaced that black wire.

I mounted the new unit underneath the battery, where the old rectifier was, fashioning a bracket that holds it off the battery box frame about an inch to ensure adequate air flow. I wired the new plug (3 white, red, black) and ran the green and brown wires up to where the green and brown wires enter the wiring harness. Long story short, I'm confident that I hooked things up correctly (I could still be wrong however).

I started the bike and took a voltage reading at the battery.....almost 18 volts at 4000rpm! That's not good. In fact it is 14-15 volts at idle.

Something just came up and I have to cut it short for now.....I'll try to get more details tomorrow. But....what the heck? How come my speedy regulator ain't regulating? Ideas? Thanx in advance

 

[Jim]

Show us some pics of how you wired it (connectors and such).
For it to be that high, either the new regulator is bad (not unheard of), or you somehow wired 12v power straight to the green wire.
Or possibly a problem with the green wire inside the harness.

 

[Jim]

... and welcome to the forum!!

 

[Its been a long time]

There's been a fair number of these bad out of the box? If it's wired correctly, I think the OP would be wise to send it back for a refund. Then follow the excellent guide here on using a standard bridge rectifier and automotive regulator. Worked great on my 77 650D.

 

[Banzaibob]

Here are some pictures that hopefully illustrate the where and how. The first pic hopefully gives an idea where the reg/rect is mounted. There is plenty of clearance and none of the wires are frayed or in contact with any other components.

These next photos give a clearer shot of where the wiring terminates; I don't have any colors "crossed."

I tried to upload a .MOV file of the voltage while the bike was running. It would not allow me to do that. Basically it reads about 18 volts at 3500 rpm and slowly cooling down to about 15 volts at idle. It is an AGM batter. Resting voltage this morning was 12.9 volts.

 

[Jim]

The green wire sends power to the rotor brush to energize the rotor. It's a pulsed output that depends on the current state of (batt) charge. Less/shorter pulses as you reach full charge. It sounds like the green wire is sending a full 12v to the brush that's keeping the rotor energized continuously, causing the overcharge.

So either the regulator is bad, sending too much/continuous power to the rotor, or there's a short somewhere between the batt and the green wire... assuming it's wired correctly.

Try disconnecting the green wire coming out of the regulator and see what happens. If it goes to "no charge," then it's likely the regulator is bad.

If it's still overcharging, then there's a constant 12v on the green wire that's not supposed to be there.

 

[Banzaibob]

The green wire sends power to the rotor brush to energize the rotor. It's a pulsed output that depends on the current state of (batt) charge. Less/shorter pulses as you reach full charge. It sounds like the green wire is sending a full 12v to the brush that's keeping the rotor energized continuously, causing the overcharge.

So either the regulator is bad, sending too much/continuous power to the rotor, or there's a short somewhere between the batt and the green wire... assuming it's wired correctly.

Try disconnecting the green wire coming out of the regulator and see what happens. If it goes to "no charge," then it's likely the regulator is bad.

If it's still overcharging, then there's a constant 12v on the green wire that's not supposed to be there.

The rotor brush energized by the green wire produces a constant 13.9 volts (the resting voltage after receiving a charge of 17 volts from the reg/rect.). If the green wire is unplugged, it shows 0 volts at the brush (no charge). Also, if the brown wire is unplugged it will also show 0 volts. There is no intermittent or pulsed current going to the brush. The other brush shows 0 volts.

 

[Jim]

If the green wire is unplugged, it shows 0 volts at the brush (no charge).

If that's the case it doesn't look like there's any stray voltage to the brush. I really can't think of anything else other than the regulator then.

Anyone??

 

[Banzaibob]

If that's the case it doesn't look like there's any stray voltage to the brush. I really can't think of anything else other than the regulator then.

Anyone??

Let me ask you a couple of stupid questions:

All voltage measurements are to ground using a Fluke VOM. On the other brush, there is 0 volts. Is that correct?

Disconnecting the green wire produces 0 volts on the "hot" brush. Disconnecting the brown wire also does the same. Is that also correct? What circuit does the brown wire power on the '75?

With all of the wires hooked up and charging the battery, (overcharging, that is) there appears to be a noticeable drag on the engine. Granted, these are small throttle apertures with no other load on the engine. When the green wire is unplugged ( or the big white plug from the stator for that matter) rpm rises quite noticeably. It's a pretty dramatic effect. Should this be attributed to the fact that the overcharging alternator is simply working too hard?

 

[Jim]

"All voltage measurements are to ground using a Fluke VOM. On the other brush, there is 0 volts. Is that correct?"
Yes. The black wire brush is a ground. Testing ground to ground will always be 0v.

"Disconnecting the green wire produces 0 volts on the "hot" brush. Disconnecting the brown wire also does the same. Is that also correct?" What circuit does the brown wire power on the '75?"
Yes. Brown is main system power. That's why it goes to the regulator... so it knows what batt voltage is so it can regulate and to feed the green wire to energize the rotor.

"With all of the wires hooked up and charging the battery, (overcharging, that is) there appears to be a noticeable drag on the engine. Granted, these are small throttle apertures with no other load on the engine. When the green wire is unplugged ( or the big white plug from the stator for that matter) rpm rises quite noticeably. It's a pretty dramatic effect. Should this be attributed to the fact that the overcharging alternator is simply working too hard?"
No, that's not normal. the rotor should draw about 2.5A. That comes out to about 30 watts of power from the engine. Keep in mind one horsepower is about 750 watts... so a very small fraction of a HP drain. That should/does have a slight change in RPM, not a big one. I'm wondering if there isn't maybe a short in the rotor. Rotor should read about 5Ω across the rings. Suggest you check that.

 

[Its been a long time]

From the above discussion, I'd say it's probably a failed regulator. If the regulator is providing a continuous 13.9v to the green wire, the alternator is generating continuously unregulated. Rotor is fully excited and unregulated. Perhaps producing enough power to present a noticeable drag on the engine at tick over? Unregulated continous rotor excitation also explains 18v at 4000 rpm.

Sounds to me like it's yet another dead on arrival regulator from that shop.

(As an analogy, I have noticed that on some engines - Turning the lights on and off with a ticking over engine changes the electrical system load enough to notice the engine idling speed change as the lights are turned on/off).

 

[Banzaibob]

Rotor should read about 5Ω across the rings. Suggest you check that.

Mine measures 6 ohms. I'll attribute that extra ohm to imperfect conditions/dirt/etc.

 

[Banzaibob]

Update from this week:

On Tuesday I send in an online "return form" to Mike's XS for the Regulator/Rectifier. An employee responded back the next day and asked what the make/model/year was...what kind of battery I had....and if I had done a diode check. I told him the model and that I had a brand new AGM. I also told him that the results of a diode test revealed that across all 3 white wires, it appeared that the diodes only flow electricity in one direction; the diodes appeared good.

Next day I sent some of the photos that I posted here in order to show him that the wiring is indeed correct....no response. The next day I decided to delve a little farther in. I originally purchased this regulator/rectifier because the old stock system appeared to need adjustment and I wanted the convenience of a "set it and forget it" solid state charging system. So, in order to further test and troubleshoot the system, I hooked up the old system and adjusted it to charge the battery at a modest and reasonable 13.7 volts at 3000rpm. I sent him another email that described the results of hooking up the old reg/rect......no response.

Anybody know someone at Mike's XS? Who should I talk to?

I'd really like a replacement that works. If not a refund. If not, someone in their tech dept. to tell me what I'm doing wrong.

 

[5twins]

Personally, I would go for the refund, put about half of that money back in my pocket, and "roll my own" with the rest, lol .....

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

And let this be a valuable lesson to you - DO NOT buy anything from Mike's without checking and asking on the forum here first. They sell some real junk and this reg/rec is some of it, lol. Many reports of these bad right out of the box.

 

[Its been a long time]

+1 ^^^^^ What 5twins says.

 

[Banzaibob]

Personally, I would go for the refund, put about half of that money back in my pocket, and "roll my own" with the rest, lol .....

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

And let this be a valuable lesson to you - DO NOT buy anything from Mike's without checking and asking on the forum here first. They sell some real junk and this reg/rec is some of it, lol. Many reports of these bad right out of the box.

Evidently you can only respond and communicate to Mike's XS through their online return message page....the return emails I sent do not appear to have been received. However I was able to work it out with them and they are going to except the return. I'm not going to complain about them......yet.

Rather than ask for another unit, I'm simply going to clean up what I have and try to go with that. I tend to think that the actual problem was not only improper and sketchy grounding, but corrosion on the contacts and general old age. I got the stock unit to charge at 13.7 volts, that's doable for a 50 year old classic bike. But I would like to adjust it further to read 14.5 volts at 4000rpm.

 

[arcticXS]

The oem regulator is adjustable. I tweaked mine a bit some years ago

 

[Its been a long time]

Evidently you can only respond and communicate to Mike's XS through their online return message page....the return emails I sent do not appear to have been received. However I was able to work it out with them and they are going to except the return. I'm not going to complain about them......yet.

Rather than ask for another unit, I'm simply going to clean up what I have and try to go with that. I tend to think that the actual problem was not only improper and sketchy grounding, but corrosion on the contacts and general old age. I got the stock unit to charge at 13.7 volts, that's doable for a 50 year old classic bike. But I would like to adjust it further to read 14.5 volts at 4000rpm.

The settings for the electro mechanical regulator are given in the manual. I suggest you test and set using the procedure in the manual. You can then fine tune it with the bike running. It might be in very good condition. The 1977 regulator on my 650D looked almost new internally and the two gaps you check on the contacts were absolutely fine. Not bad for 48 years old really.

 

[Banzaibob]

I didn't know if I should start another thread about adjusting the regulator....I'll leave this here for the time being.

I adjusted the regulator today. It actually appeared to need more cleaning with sandpaper and contact cleaner. It appears that it did not consistently make contact and trigger the field coil wire. I cleaned it thoroughly and set it for 14.5 volts at 4000 rpm with no load on the engine (more on that).

I decided to fashion a mount for my voltage meter and ran a hot wire to the accessory battery charger terminal and an alligator clip to the fins on the engine for ground. The plan was to take about a half hour, 20 mile ride just to get a feel for what the charging system was doing.

In a nutshell, I'm pretty satisfied but still questioning what may be going on. After starting and letting it warm up, I took off down the half mile of gravel from my house. With very low throttle settings and not getting much above 2500 rpm, the voltage was around 15.2. However once out on the paved road in 4th and 5th gear, 3000-4000 rpm, the voltage would settle down to around 14.2-14.5.

The curious thing though was at highway speeds under hard acceleration or heavy loads like a hill, with the rpm above 4000 and with plenty of throttle the voltage would drop, between 13.2 and 13.7 volts. I tried a few experiments like slowing the bike down so where the voltage would climb with lower rpm, and then get on the throttle. Again, 2000-2500 rpm I would be looking at around a max of 15.2 volts....and then after accelerating to highway speeds/loaded it would again sink down to 13.5 volts or so. One thing that I thought it might be was that under hard load, the coils might be pulling some extra current....that is quite a bit of current though and that might be a sign of problems with my coils getting old. I might add that at idle, 1100 rpm, it reads 12.65-12.75 volts.

I'm actually pretty satisfied with these voltages. But I am kinda curious as to what the regulator is doing by putting a relatively "hot" charge at low rpm/load and then a sort of mediocre charge at highway speeds/loads. Any thoughts?

 

[5twins]

Once I installed a volt meter and was able to monitor the charging output, I found it very erratic with that old original regulator. Around 3700 or 3800 RPMs, it would suddenly drop off, coming back by 4K RPMs. I figured the vibrations at just under 4K must be just right to mess with the points inside the regulator. And I also figured that constant unnecessary ramping up and down of the charging output was working the poor old rotor harder than need be. So, I decided to switch to the automotive VR115, and I'm glad I did. Not only does it put out a steady 14.2 to 14,5 volts (seems to put out higher when it's colder outside), but it also reduces the output by a few tenths of a volt after the battery is recharged from electric starting.

I'd advise you to switch to the VR115, you won't be sorry.