Regulator / Rectifier / Stator - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old 01-19-2006, 08:32 AM Thread Starter
Vulcan Verses
Join Date: Jan 2006
Posts: 178
iTrader: (0)
Regulator / Rectifier / Stator

Also See Getting at the R/R

On the Yahoo VN750 site, go to “Files” (left hand side of the page), then “electrical and lighting,” and then “RR and Stator.”

Have your stator checked when the engine is very hot. I now know of two bikes that the stators failed to check out when hot, but tested ok cold. (one of them was mine) You should also be able to tell if you have a voltmeter on the bike. Check the system voltage after the bike's good and hot.

What are the symptoms of R/R failure?
Try this check list put together by Trent:

When the R/R fails (open or shorted diode(s)), the battery will not be charged properly as the bike is running. Eventually the bike will have no battery power... it WILL still run, but you have to keep it going since it will not restart (no current for the starter).

James had this issue and actually ran quite a while without a good battery. Not sure how he started the bike, may have pushed and dumped the clutch. Anyway, a bad R/R, if diodes short, can put excessive load on the battery and cause stator failure, which requires an engine pull. Do not panic, it is probably not that, and I do some testing first. Measure the battery voltage when the bike is running at about 3K RPM, should be around 14V if battery, stator, and RR are OK. If not, let me know and we can go from there.

Now since you said you can keep it running with the choke on, this indicates it very well may be fuel starvation. This is not a big deal. Check your float bowl levels. It takes 5 minutes and requires a clear vinyl tube attached to the bowl drains. If you need more info on how to do that, let me know. Does the bike backfire? If so, the fuel starvation could also be caused by an airleak on one of the carb boots. Could also be the plug wires or ignitor. Before going into all this, check the battery voltage first and advise. Starman.

Q: From what I've picked up in the postings from this group, it appears that the VN750's charging system has a few basic design flaws. Can someone confirm if what I understand is correct? It sounds like the stock voltage regulator (R/R???) overheats, tells the alternator to crank up the juice, which then causes failure of the stator. Since this sounds like something that a little preventative maintenance and field modifications would fix, I just want to make sure that I'm understanding the issue correctly. I've seen this happen on the various cars I've owned/fixed over the year's, but it appears it's a heck of a lot easier to replace most car's alternators that a VN750's stator.
A: You're correct Keith. Relocating the R/R (a bracket along the frame over the left passenger peg is the most chosen location)or removing the goat's belly will eliminate the heat source. The main preventive maintenance is installing a maintenance free battery. With the two combined you can rest a lot easier and enjoy more ride time *S*

A: I agree with Dianna. But I would add, you don't even want to think about replacing the stator unless you are forced to. It's a very tough job even for a veteran cycle mechanic. It is expensive, very time consuming, hard to do, and should be the last resort. And it's a job you can avoid if you heed everyone's advice. Do everything you can to keep the stator you have working. Lose the goats belly or move the R/R and get a sealed battery (WestCo), immediately, of not sooner. You will be very glad you did! If not, you will eventually wish you had! I bought my 1992 VN750 with a burned out stator (didn't realize it at the time) and eventually replaced it with an Electrex stator & R/R...myself. That's a job I do not want to tackle again. But, if you choose to do it yourself, there are a lot of really good people in this Yahoo group who can help walk you through it. They helped me a lot. Good luck.

Q: O.K. , heres the deal, I have replaced my fusebox, R/R, gone through 2 batteries, ( I now have a sealed WESTCO. ) ... Still battery will not stay charged during riding. I have a feeling that it is the stator. But, Here is the question. What is it exactly that the stator does? and what is the harm in me just keeping the battery on a BATTERY TENDER when I am not riding?
A: Harold...what symptoms indicate to you that the stator is NOT charging?? Here's a simple test I use... hook up a voltmeter to the two access leads under the right cover. Set to 'DC' voltage, and take the bike out for a spin. You should see the voltage vary from ~12.8 volts to ~14v depending on rpm. This variance is not linear...meaning that it will not read the same all time for all rpms, it depends on a few factors. The important thing is that you see voltages in the charging range of 13-14.5v consistently. You could do the above on the centerstand, also. Also, this is why a lot of us have volt meters installed on our bikes...I am constantly checking it out as I ride.

A: The first thing I suggest is checking your stator using the information on this page:

The purpose of the stator is the same as the alternator in your car. It supplies power to charge your battery and power all your lights and ignition system via the regulator/rectifier. When my stator failed the first time, the headlight began working intermittently because the stator could not supply enough voltage to energize the headlight relay, but there was enough voltage to power the ignition, although there was a decrease in my top-end speed because the motor would miss a lot and lose power.

If you never ride far from home, the choice is yours as to what you do, but there is no guarantee that the stator won't completely fail and leave you stranded when the battery completely loses charge, which doesn't take long. I must also note that the stock stator and regulator/rectifier combination can not supply enough power to charge the battery at idle. You need to get that puppy up to highway speeds for a while to do that. The Electrex stator and regulator/rectifier setup does supply about 13.5 volts at idle, so it would appear the battery can be charged, or at least maintained, while idling the motor.

As you'll see on this page: , it is a lot of work to replace the stator, but it can be done if you have patience, plenty metric tools, and a second pair of hands to help you pull and re-install the motor.

To do so, see this page: . I've had the motor out of my 1990 VN750 three times, so if you want to take on the task, I'll be glad to answer any questions. Good luck!!!

Check out Starmans link on my web page for fusing the stator. We (well he did most of it) did the work at his place. Go to for his link.
If you remove the goats belly (GB), you remove the heat source to the R/R. With the GB removed the R/R will get more than enough cooling ventilation with the air flowing up through the empty frame where the GB was. There is really no need to move the R/R unless you just love your goats belly and want to keep it. Cost me $20 at the local muffler shop for them to make two pipes & clamps to replace the goats belly. The bike is lighter, runs better, cooler and sounds better. So my advice is, leave the R/R and lose the GB. JC

Regulator ground question I asked Electrex about this a couple years ago - there is NOTHING inside the r/r that is electrically connected to the case. The case is just a case (and heat sink). So, adding a ground wire does nothing (sorry Gypsy). Kenny in WV still lurking sometimes
Sure it does, it grounds the case. In any event ,Bulldog's relocation bracket is made of aluminum which will ground the case anyway. Freak
Electrically connecting the R/R case to battery negative doesn't affect the regulation. Mechanically connecting the R/R case to a thermally conductive media could affect the performance of the regulator.

Last edited by Vulcan Verses; 01-19-2006 at 08:40 AM.
Vulcan Verses is offline  
Sponsored Links
post #2 of 2 (permalink) Old 01-19-2006, 08:32 AM Thread Starter
Vulcan Verses
Join Date: Jan 2006
Posts: 178
iTrader: (0)
R/R Update - Convert your OLDER unit to NEWER unit
Electrex was clear to me when I reported my original findings. It
makes complete sense to me to tie the brown to red to lower the
voltage and provide more stability. When the brown wire is tied to the bike it tells the regulator to make up for IR losses in the bike
wiring... and if those wires are not very good, the regulator will
boost it's local voltage to make up for that.

Connecting the brown to the red wire is only changing the sense to
the regulator output, where it should be.

I was running somewhat overvoltage with the sense wire, now it's
right (and more stable) by using the latest pointed-end which
has an internal connection of the brown wire to red output.

See my previous posts on this. I posted all the links to the
schematics which shows what I am talking about. If any questions, you
know where to find me !
From: "Dan Morgan"
Subject: Re: [VN750] Electrical Problem continues.
- How to check out the R/R

If you have the Kawasaki Service Manual, you will find R/R checkout on page 15-18. If you don't I will list what is there for you. Quoted from the manual as much as possible: Regulator/Rectifier Inspection Remove the left side cover. Pull out the connector. Be sure to set the hand tester to the 100 ohm range and zero the meter(Not necessary on a digital meter) Check the resistance between the regulator/rectifier terminals as follows(there is a chart and picture in the manual which I cannot reproduce right now but I will try to put it in words for you)

A1 A2 A3 All Alternator Terminals --- --- --- Connector with pins facing you and notch at bottom --- --- ---

G M B G = Ground M = Monitor B = Battery --|__|-- (Hope that came across right)

Measure B to M - should read infinity

Measure B to G - should read infinity

Measure B to A1, A2, A3 - should read infinity

Measure M to B - should read > 10K ohm Measure

M to G - should read > 10K ohm

Measure M to A1, A2, A3 - should read > 10K ohm

Measure G to B - should read between 0.4 to 2K ohm

Measure G to M - should read between 1 to 5K ohm

Measure G to A1, A2, A3 - should read 0.2 to 0.6K ohm(200 to 600 ohm)

Measure A1, A2, A3 to B - should read 0.2 to 0.6K ohm(200 to 600 ohm)

Measure A1, A2, A3 to M - should read infinity

Measure A1, A2, A3 to G - should read infinity

If there is more resistance than the specified value, the unit has an open lead and must be replaced. Much less than this resistance means the unit is shorted, and must be replaced. Hope this helps someone out there. Dan Morgan

Q: Here is what I always wondered. Some people insist that the energy generated by the bike's charging system needs to be used, or the stator and reg/rec will have to heat up to dissipate it. They say that adding electrical accessories will result in less stress to the charging system, since the charging system does not have to dissipate the excess energy. And since the charging system does not have to dissipate energy, it will not be subjected to heat associated with dissipation. Now, if I recall correctly, energy dissipated in an electrical circuit is dependant on current and resistance. If there are no electrical accessories attached to the bike, there will be a voltage, but current will not be flowing through the charging system at all. Adding accessories to the bike will result in more current flowing out of the charging system. More current means more heat within the charging system as well, no? And if that's the case, adding accessories will make the charging system hotter, not cooler. So what is the truth? Should I try to reduce electrical requirement by using LED bulbs, etc., or should I not be afraid to add accessories as long as the battery gets charged at cruising speed? Technical answers are welcome. I really want to understand this. Thanks, Masa
A: Masa, I think you are asking: "how can adding accessories be better on the stator". Hope I can help here by attempting to show that's not always the case, and it's more involved than that.

First some terminology
I=Current (I know, pretty stupid)

It is true that V=IR (voltage=current X resistance), or I=V/R. So the lower the resistance, the higher the current for a given voltage.

Adding MORE accessories is the same as .... "increasing the load" ... is the same as "decreasing the resistance" ... is the same as "increasing the current" since (I=V/R). You can see that as R gets less, the I gets higher. Stator Current: "Use it or loose it" - the current generated by the stator can be used by YOU (your accessories) or go just to the regulator !

The voltage regulator / rectifier (the one that has been talked about so much), will "dissipate" or "sink" or "bleed-off" or "dump" any voltage over a certain point, as the regulator ITSELF is actually a "load" or resistance just like the headlight or added accessories are. Since it only consumes current when the voltage is higher (which is why it gets hot BTW) you can "bleed" some of that current away from the regulator and use it for other things !
This is KEY: If you "bleed" too much, the regulator cannot do it's job, and it stresses the stator. However, not adding accessories will not wear out the stator, the extra current just goes to the regulator.

Note: Driving lights, horns, heating pads all take a lot more current or consume a lot more "power" or "watts" than do cell phones, CD players and such. The current of those is negligable.

OK so to recap, - stator current, use it or loose it

- regulator takes current itself
- but you can use the current for something else (to a point), no need to use it to heat the regulator (to a point, the regulator still needs to 'regulate' which takes some current)
- too many accessories stresses the stator
- no accessories will not stress the stator any more (the unused current still is 'dumped' into the regulator).
- lights, horns, and heating pads take a lot more power than cell phones, CD players

Yes, this is technical and can get confusing. If you need any more explanation, just let us know. That's what this board is for.

Q: was wondering about packing the connectors with the dielectric grease. If this grease conducts electricity, wouldn't there be a risk of shorting out from one connector to the next in a multi-connector plug like that used on the R/R?
A: I have used dielectric grease on multi connectors for years with much success. I don't think it conducts well enough to pose a threat, but it does an outstanding job of keeping out moisture & dirt. It is also frequently used on boats to seal electrical connections. Mike Palm Bay, FL

I have read through all the opinions and suggestions... Fused the stator connections and packed all connections with dilectric grease.
A: Dielectric grease is an insulator. From somewhere: "Dielectric strength is the ability of an insulator to withstand potential difference. It is usually expressed in terms of the voltage at which the insulation fails because of the electrostatic stress. Maximum dielectric strength values can be measured only by raising the voltage of a TEST SAMPLE until the insulation breaks down."

The grease keeps out moisture, dirt, etc, protecting the connectors. The grease is displaced by the connectors sliding together - they must still be clean (not corroded) and make good contact. The surrounding grease just helps to make sure the connection stays good (not corroded).
Kenny in WV

i'm trying to get my priorities in order as to what i need to do to and get for my bike. the other posting by vince to the new members pointed out the r/r relocation is a priority. mechmo question

# 2 - how much is that gonna cost to get done ? (i see the part alone is about $120)
This is a relocation - not a replacement. Unless your stock unit is bad there is no need to replace it. The idea is to get the R/R out from under the battery box where it's subject to battery acid spills and extra heat from the goat's belly.

# 3 - it appears to be a "custom" job ? Would have to take directions in to the mechanic, or should a place that services kaws be up to speed on this?
The R/R is not difficult to do and requires little in the way of hardware. Check out the files in our database on moving the R/R. I bet you'll see that you can do it yourself.

# 4 - does the popping from the bikes do any actual harm to the bike/engine, or is it something fixed because it is an annoyance?
It's just an annoyance. Mine hardly does it at all and I've not coastered it yet. Since I'm planning to put some V&H Cruzers on it this year, I probably won't bother with coastering until I do the install. BTW - the #1 priority is to replace the stock battery with a maintenance-free type. From all the posts seen here and on the VROC main board, the stock battery is the #1 culprit for causing electrical problems that can be expensive and disastrous. The Westco and Yuasa brands come well recommended but there are other good ones out there too.

I agree 100% with MokiMan. #1 is the battery, and #2 is relocating the R/R. However, if your bike still has the goat belly, it will be more difficult. I think you have to remove it in order to get at the R/R. Is that correct, MokiMan?

Last edited by Vulcan Verses; 01-19-2006 at 08:36 AM.
Vulcan Verses is offline  
Sponsored Links
Closed Thread


Quick Reply

Register Now

In order to be able to post messages on the Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Once registered, your User Name"cannot be changed". We can make exceptions within 7 days, but after that, it is set in stone.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome