Evan, I have owned quads and bikes for over 30 years and I always just fumbled around with trying to figure out what's wrong with electrical/starting issues. Sometimes I'd get lucky and fix the problem, but usually not. Watching your videos has not only given me the necessary knowledge and thus the confidence to diagnose electrical issues, but it's actually excited me to the point where I want to learn more about these systems. Thank you (and RM Stator) for taking the time to educate people like me...for free!! RM Stator has a life-long customer in me due to both the high quality informational videos as well as the extremely high quality and durable products you produce.

4 years later and this is still the most helpful and easy to understand tutorial i have found to test these. Thank you for taking the time to put this together

This is the best detailed test and explanation video I've found thus far! Well done!

Dude...what a stellar explanation. You cut straight to the chase ...eliminating the weather of the day, your wives menstrual cycle. You dumb it down just-right... Explaining the process well enough that it's understood by an amateur but also providing enough information for the student to ask relevant/educated questions. In all my years of using KZfaq this is the first time I've taken the effort to post a comment. Thank you.

This was one of the videos I watched to figure out the charging problems on my 2000 Honda VFR Interceptor. Did the other tests and now that I know how a voltage regulator/rectifier really works, I was able to conduct the test and found one leg of the diodes not working correctly. Easy removal, ordered the part, and now we wait...Thank you for the clear, detailed, and concise advice. I'm not a mechanic by any means and electrical has always caused anxiety, but this video made it much easier and increased my confidence to undertake this. Thank You!

Excellent video! The clearest and simplest explanation I've seen around. Totally recommended to be watched by anyone wanting to understand how this little critters work

Excellent. No waffle. No annoying music. Just clear description and facts.

I see there were 17 dummies that tried watching this video and didn't like it cause they lacked understanding... Been a while since I've had to work on this stuff, and this video was a GREAT refresher course. Spot on Dude!! Good job! I gave it a Like and saved it to my Favorites! 👍

Wiring harness eaten clean through and am having to figure out the whole electrical system and testing all my electrical parts. Evan has the best videos that explains everything in simple terms. Thank you for the videos!

you really help a lot for us but i wonder why there are still people giving a thumbs down to this video. watching from the philippines.

The best explanation on the web!!The MOFSET values is what i was looking for!

Hello Evan! I watch a LOT of KZfaq vids. Your video explaining R/R is by far the best educational video I've seen. Very well done. I felt that if I never even heard of a motorcycle I would understand what you were talking about. Looking forward to watching more of your vids! 👍👍👍

DUDE!! You deserve a prize! Not just for explaining the function of a voltage regulator but for making it fun and easy to understand. Maybe I was just ready for this but you made it easy to understand with this diagram. Now the whole component seems so simple. Now splicing wires to make a change from like the four connecter plug on the smaller 50cc regulator are going to seem so simple. I'm sure I'll goof some stuff up but that will only be because of curiosity in seeing what might work, This was just great!

Thank you for taking the time to make this video. Dirt bike wiring is like a big mystery because it is so simple, but few people have this level of understanding and of those people they do not take the time to explain it.

That was an incredible instructional video. It was clear, concise, and for me made complete sense on knowing how to analyze my charging system.

All I can say is after watching your video I finally get it. Thank you for taking the time to put this video out.

best reg/rec testing demo I've seen...thanks for putting this up

Highly educational video. Even I was able to get it.

Great! Very helpful, very clear demonstration that made me understand clearly how a rectifier works and how to diagnose it as well and the voltage regulator. Thank you very much!

Excellent tutorial! Remembering the drawing in your mind (diodes' direction and battery's plus and minus sides) makes it so easy to understand how to measure between each connector pair and what the results really mean. Regulation was very informative as well. Good job, thank you!

Really great explanation! Working on rewiring a GY6 engine with an 11 pole stator upgrade and have to rewire the bike to accept a 6 pin regulator/rectifier. This is going to help a lot!

Really helped explain what I was actually doing when trying to test my regulator/rectifier. Thank you for the informative video.

Great man, lot of love from South Africa.

Best explanation and demo I've ever seen on this subject!! Well done!

Brilliantly explained....one of the best video I have come across for troubleshooting regulator rectifier

I love your set up for actual testing. I had not thought of using my lathe to spin a flywheel over the alternator. However, in my own research of the charging systems, I'm something less than impressed. After going through 4 regulators in 5 months, I've begun taking them apart. (Yes, it's a lot of work but you can get the potting epoxy out of there.) Of course, using 1960s technology in the 21st century is rather like going moose hunting with a pocket full of rocks and a sharp stick. SCRs shunting 20 Amps to ground in an age of high power MOSFETs??? I'm disappointed with the ratings of the components. There is virtually no safety factor which makes the regulator very unforgiving. But it's also the only application I have ever seen that has the heat from the components must pass through the circuit board to be dissipated. Circuit boards do not conduct heat. I have also found as much as 1/8th inch of epoxy between the circuit board and the case (heat sink). It seems there is nothing to insure the circuit board does not "float" up and away from the cooling surface, to be suspended in the epoxy. By the time the case gets warm, the components are burned out. Mine is a 30 Amp alternator. Short-circuit current, at 1500 RPM is 29 Amps RMS. (That's 42.3 Amps peak) So 35 Amp components won't play long. Open lead voltage on the alternator, at 1500 RPM, is 60 Volts RMS. (98.98 Volts peak) 60 Volt rating on components? Really? Then more than 1/8th inch insulated gap between the heat source and the cooling surface? The last one I put in worked for exactly ten seconds. With those components, heat dissipation is EXTREMELY important. I'll build my own. The components will have a thin piece of mylar between them and the cooling surface. The circuit board will be above them. And why are my 44 Amp components physically six times larger than what I uncovered in the epoxy? They still fit inside the old housing. What I found in the epoxy would appear to have been developed during a wild office party, and then careless workmanship added for good measure. "Engineers left unsupervised." Talk to someone from MIT, have them put a "MODERN" regulator together for you, and you'll never have to replace it again. Added advantage... With a constant 14.2 to 14.4 volts out, you won't have to add water to your battery every other month.

This video is a godsend for troubleshooters with limited knowledge. Bike shops owners hitting the dislike button. Great video!

The diagrams, explanation and demo were very helpful. Thanks.

Omg he speaks english good, he simplifies it and breaks it down. Ugh finally thank God.

Retired engineer with Harley losing charging while on the road. Great and straight forward explanation. Are these rectifier regulators usually failing due to over heat. I have a chrome basket over top of the reg which may limit heat shedding.

I am impressed with stator set up for checking regul8orz!

cette vidéo est excellente pour comprendre comment tester un régulateur merci

very professional and clearly explained. thank you. i have tested 3 reg/rects following the same steps and all 3 passed but when I connect the red wire from the units to the battery's + and the black to the - there is a short (sparks and melting wires). Any ideas why this is so? It's a 97 suzuki savage.

Great video, When I put my black meter lead to batt pos i get 0.5v on 3 phases. When I put black meter lead to batt neg i get OL for 2 phases but it bells out on the third. Does this mean the rectifier is broke?

I absolutely agree, one of the best explained videos there is on the matter, well done and thanks

Awesome video. Have a question is there a sequence in the yellow wireing because my bike don't have the original connector?

Very well detailed test. Best I have ever seen.

Do you need a capacitator / battery in order for the rectifier regulator to work properly? Or can you simply clamp the multimeter on the DC output?

Best explanation I have seen, very valuable

I really enjoyed the video on testing rectifier/ regulators. I have a UTV that I am constantly having to replace the regulator on. Could you do a video on why regulators may fail and show some trouble shooting steps?

I have a 3 phase chargeing system , with 3 wires out red goes to battery? Green goes to ground ? Black goes ? 3 yellow goes to another connector,

Per the chart my test results are all good, is it possible my regulator/rectifier is still defective? I’m charging at 17volts but I’m told stators usually do not overcharge, they undercharge when dropping a coil.

What would cause the regulator to intermittently spike at 18 volts then go back to working normally again, if something failed wouldn't always be failed, can shunting switches be bad then start working correctly again

Great video. I get zero readings when connected to my 3 wire regulator. All I get is the OL on all 4 phases. Ordered a new one so lets see how that one checks out.

I find out that three diods are dead! They are "closed" in both direction. It is either the three up or the three down in your drawing. But all seems work fine with only three diods? Charge is about 14.6V. Battery 13V, fully charged. I suppouse the voltage is pulsing, but my voltmeter don show that. Should I change rectifier anyway?

Can you explain what signal is being sent from the reg/rec via the white/violet wire to the ecm on a 2004 skidoo 600 SDI, it causes the eco to turn on and off the main power relay to power up and down the speedo cluster.

Awesome video, very detailed and well explained. I have a question, if you tested the DC output of a rectifier/regulator without a battery connected, would it read the same voltage as the stator? Because there is no reference voltage and the switching would be trying to put out as much power as possible?

9:37 I see you removed the yellow wires from the plastic housing/connector for the test. Do they have to go back in the plastic housing/connector in the same order for the charging system to work right? What if you didn't keep track, and put the yellow wires back into their plastic housing in the wrong order?

understood this video very well, thought I diagnosed my bad rectifier well... but my new rectifier tests exactly the same. Haven't installed it yet with hope I can still return it. Thoughts?

My new RR passes test 1, 2 and 4. Test 3 (Meter Black to Battery +) should show readings but doesn't. My reputable supplier in the UK suggests I connect it to the bike (a 2015 Royal Enfield Classic 500) and see how it goes. What symptoms would be apparent if the RR was, indeed, faulty?

Great detail instruction

Learned a ton! I’m working on a 1966 Honda dream ca78 motorcycle that has an archaic electrical system. Voltage at idle is a consistent 8-9 V when the rpms increase the voltage jumps around and varies between 10-16 V. I’m assuming I need a new regulator/rectifier. I have three wires leading to the regulator rectifier + - and one to the armature I presume. Could just about any 12v 3 wire regulator work? Do you guys have on for sale that could fit the application? Thanks for the video and help!!

Great video, very informative. But I have one question, I have a 2001 Honda Shadow 750 and the wiring coming from the stator had gotten hot and the connector was in really bad shape. I cut the connector off the old connector and installed a new one. When I found the issue two of the wires were in really bad shape with one of them completely disconnected. I believe I got the wires back in their original positions as it seems to be operating properly but was wondering, does it matter what order/position the (yellow) wires from the stator are in when connecting it to the rectifier/regulator? Can they be in any position? Also, can the system work with one wire disconnected?

Excellent video! Could you explain why @12:00 MOSFET regulators meter BLACK to Battery + spec will be 0.09-0.11v? Why are their reading different in this direction?

Explained in great detail. Thanks for the video!!!

5.38 you state that the current is producing heat and thats why the unit has a large cooling surface. However the heat of the current is produced in the stator-coils and the shunt has a close to zero resistance and will generate very little heat. The block gets hot by its rectifying proces.

very informative, more than I can comprehend right away. once I think about it for a while it will eventually be understood,

I would also like to see if you can test the regulator with a non running engine, only crank. I have a no spark issue, new cdi but trying to rule out the regulator. Rectifiers work fine.

Hi, is there a sequence for wires when you connect them from stator to the regulator/rectifier ? Does it matters where any of the 3 yellow cables enter the regulator/rectifier (also yellow) ? Someone cut the socket that comes from the stator. TY

Thanks for that guys - away now to test mine. All the best from Glasgow

Great video but can you do an explanation on 7-8 what are the extra wires for on a 7 or 8 wire regulator are they extra grounds or hot wires? ? My stator tested good I’m trying to test regulator on my 08 brute force 650 but it has 8 wires. 3 yellow from stator and 5 on output of R/R

Awesome info and explanation....with the setup of machines to stimulate the bike running👌👌👌

Great video. I had a question though. A bit new to this stator rectifier deal. So I got a relocation kit to put my reg/rec in the front of the utv. But having issues with charging now. I'm wonding if the harness has the stator output cables to the reg/rec flip flopped.. say # 1 on stator is connected to #2 or #3 position on the reg/rec connector. This would cause a issue correct? My voltage guage shows 11-11.5 vdc at idle now instead of 12-14 vdc. When I test the stator it tests good 20vac at idle on all 3 legs, Rev up and all 3 legs jump up 50-70vac. I tested the rec/reg and seems like all 3 legs are reading correctly... .5 at each. But I noticed it's getting quite hot quite quick and low voltage reading at battery and car idles funny. Thank you in Advance 🤘🏼

Great video on the topic of rectifiers and regulators. Well done.. Should be mandatory viewing for all owning a Ducati :-)

Excellent video, Evan. This helped me a lot! Thank you! Do you recommend replacing the rectifier/regulator at the same time when you replace a bad stator?

Thanks. This helps a ton! I am working on my 2008 Yamaha F40. The voltage is reading 16.1 volts at running speed. That can't be right.

my aftermarket reg/rec for honda CBF1000 shows instable voltage on DC output : jumping between 11.5 >16.5 V. I measured the courant directly on the positive and the negative wire. When connected to the battery it shows 14.2V. My Honda original reg/rec shows alwas 15.5V . The aftermarket reg/rec is supposed to be a MOSFET one.

I own a 2012 husky te 511. so diodes check out, rectifier good. but, the regulator does not climb all the way up to 14.6V . gets to about 13.7 then start coming down. any ideas on what to test next? thanks! great video

My 2007 Triumph Speed Triple has an issue trying to start. I thought it was the battery so I purchased a new one but that doesn't seem to be the problem. The issue: When trying to start the bike the starter will turn over for just a second or two and then nothing and the dash lights and headlight all go black. I tested the battery when off the bike and it says 12.95 volts but after installed and this issue arises and the dash goes black the battery, while still installed shows 1.25 volts or thereabouts, I don't remember exactly but the reading goes really low. Then I disconnect the battery and it reads just fine, 12.9 volts. When I reconnect the same sequence happens again...Headlight and dash will come on and when I push the starter button the starter will only turn over for a second or two then stop and the lights all go black. I pulled the alternator rectifier and tested the diodes and they all read fine, about .542 or so on all three and reversing polarity same results. Do you think if the regulator is bad it will cause this shutting off of system and then the low volt reading when the battery is still connected? Any input would be appreciated, Thank you

Need help: I have replaced twice my regulator/rectifier (sym vs125 2010) and it burns after less than a minute after engine start. Already checked all connections and also replaced the stator. What should I test?

great info. but I don't know anything about a multimeter, like how to set it

Hello RMSTATOR, Would it have been a better idea if when the voltage was higher than it should be, that it would go through a resistance instead of a dead short? I just had my RR go out on me, a nice bit of smoke! It turns out the connector a 2 pin plug on a 91 Sporty heated up and shorted the plug between the stator and the RR. Luckily the stator is good as it is within H-D specs and delivers 65 volts at 2500 spins of the crankshaft. I can see that if any top diode opened up it would reduce the amount of current, as that leg from the stator would not be deliviering any volts or amps. If one of the bottom diodes opened up, would that overload the other two diodes? No telling what happened to my RR. a total open between stator leads and Bat+ wire. Thank you very much for your help.

Great video, will this work the same for a single phase stator set up? (Just less diodes to check).

Can you test the output on the regulator/rectifier with out it being connected to the battery with engine running? If so will the dc voltage stay at about 12-14.6 vdc? I removed the green and red from battery and its out putting 30+ vdc with out it connected to battery and increases when i rev my engine once i connect it it drops to .4 vdc. My vac from stator is about 40vac and increases when i rev the engine. I tested the diodes and all checked good forward bais test. Also i have a brown wire what is it for? Thx any input would help !

thank you. i actually understood what was going on for a change. cheers. can you demo how to test if its the starter or the solenoid which is failing?

I have a Polaris sportsman 570 -18 with regulator rectifier oem # 4015230 and when tested, the result is: meter black to battery + = 0.480 on all 3 wires. meter black to battery - = OL meter red to battery + = OL and meter red to battery - = OL. So it does not pass the RMstator diagnostic flowchart test. I have heard that the Polaris rectifier is different than others. So my question is whether it is OK or broken?

My stator and rec/reg check out with all of the multi-meter tests, however when running the bike, at idle I see about 13.9VDC, and when increasing RPM's it drops DOWN to about 12.5VDC, does this indicate a bad rec/reg? Thanks!

qestion : in your schematic ( simplified ) the regulator part shorts the coil to ground ? that seems a big mistake because that will fry your coil to a crisp. other qestion : how much current can your regulators handle and why are there no fuses in the coil / stator lines to protect the stator coil in case of a failure to a crispy burnt flavour ? seems logical to me to put 3 fuses in the 3 stator lines .

This is beyond excellent. Thank you.

is it possible to mixed or exchange the wire from the alternator to the rectifier? i mean like if there is no terminal only wire from the alternator to the rectifier (yellow wire)? is there any specific connection for that?

My rectifier has a red, green and black...and the 3 yellow. The red and green are obvious but not sure about the black. Is it a ground that should go to the battery...or is it a hot wire for powering lights?

What would make my rectifier get very hot and start a humming noise? I have a Honda foreman 500 ( 2016) model. I purchased a new rectifier and installed it today and it’s getting very hot and humming. I noticed last week my battery kept going dead and I just purchased a new rectifier. I’m not real sure my old rectifier is bad.. any help I would appreciate it. I have looked for burnt wires or broken grounds..I don’t see anything like that.

I have a question so I did all the tests and got a new regulator, rectifier new stater and still isn’t charging my battery. Could it be my ECU?

This seems similar to a gasoline power generator? I'm getting 22 volts on the brushes, so I'm thinking towards the voltage regulator or diode rectifier. Voltage on the windings seems to be okay.

Help .. need know how to rewire 4 coil /6volt/ and recodition the coils so lives under the oil in motor as my :1982 honda cb 125s ....i want to rewire and keep 6 volt - ...or upgrade to 12.. but none made like this 1.. im not sure if others can go inside oil cavity .. like this 1.. Help.. show me what i need upgrade or remake new!

AWESOME VIDEO! I'm getting one of these for my generator.

Excellent video, but I’m still a little confused. I have 23-25 volt ac at idle between the 3 phases from the stator. About 0.2 ohm between the phases with engine off. None of the phases are grounded. So stator should be good I think? I measured the rectifier to be good also. The problem is that the output is only about 2 volt dc. Is the regulator bad?

Would like to see a video on capacitor charge system on a lawn mower. These don't have electric start and no battery. But run a 12 volt electric clutch for mower deck.

Please you guys allow met ask the following, first for not so up to standard with electronics i found this very informative. I have restored a old 12V motorcycle with of course old 56(yrs) electronics. Since I restored the bike putting EVERYTHING in its position I got i have the following problem. The system keep on blowing the the headlight globe 45/40.Some one tested the rectifier (readings were .5,1.0 and .5 the other way round zero of course. What regulator/rectifier would you recommend in this case please??? Thanks in advance

To help people understand the stator maybe add a ground symbol at the center point.

gr8 Vid! Thanks! So can a diode go bad by 1 either not conducting at all or 2 both directions. I'm guessing if 1 diode does not conduct as it should, current capacity of stator would be less. 2 if diode conducts both ways, I guess part of stator could be burned out.

What about a regulator/ rectifier that has a small black voltage sensing wire? Is it the same test?

thanks for video i have 1999 honda steed 400 the max voltage on batttery 13.70 what i sholud do ??

In my Yamaha Virago it doesn't work. You get measurements of the regulator circuit not only of the rectifier circuit, and where you expect an OL appears a 1.395V. But the rectifier-regulator works.

Hello, made the regulator test in my Africa Twin 2016 and it is not charging over 13.2 volts, even at 5,000 revs. Could a shorted circuit be the cause?... I checked the rectifier/regulator by performing the tests in this video and all measurements are withing the specified ranges. The reading on test #3 (meter black to battery plus) shows 0.096 volts readings on all three wires of the stator, so I assume my bike has a MOSFET regulator; not quite sure though.... After some months I received a new rectifier/regulator (not MOSFET though) and now the system is charging at 14.37 volts, so I guess the OEM rectifier/regulator was defective reaching only 13.2 volts.... Wonder why the OEM rec/reg became defective; could it be I jump started my bike with a car when the battery became old and didnt hold up charge anymore? Thx for the very comprehensive video!

Any reason I couldn't bench test the rectifier on seadoo jetski 3 phase? For some reason seadoo shop manual says it can't be bench tested. I get regulating test it needs to be running.

Awesome video! If I can ask a question, what might it mean if I am getting voltage in the reverse direction as you have listed. Meter black to battery positive should give voltage and meter black to battery negative should not. However, I am getting the opposite....and I have tested this multiple times to confirm.

WELL DONE, I loved this, so easy to understand I could do it!

👍👍great vid. guys.. But what if your battery is overcharging..?? Idling 14,5v. rev a bit 18 19 20 I measured my rectifier regulator in same way like you..and it showed the rectifier regulator is good.. What to do..? ( i just noticed as well that the red "bulb" on ignition switch is blinking sometimes or flashing continuously..when it happens bike has no power..if i turn off the bike and start it again few time until i notice that the red bulb on the switch is not flashing then bike has full power ) Any help from you..?

Just a quick observation: when testing diodes (1st part of your video, testing it off the bike) the units of the values you read on a DMM are in Ohms, not Volts