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Simple charging system troubleshooting.

40531 Views 57 Replies 23 Participants Last post by  Spockster
No Charts and few numbers.\

So you think you have a bad Stator or R/R ?

I am here to try to make things simple for everybody.I believe in the KISS theory,Keep It Simple Stupid !

Ok, the first thing that Has to Happen is your Stator needs to have the proper AC out put,Yes AC.Set your Meter to Ohms 1k or less.Find the bullet connectors coming from the Stator to the R/R.They are probably burned looking or nasty or both.Unplug all three,don't worry it makes no difference how you plug them back up or solder them together.More on that later.

Check from each of these leads ,coming from the stator out of the engine, One at a time to the engine case.Your readings should be Infinity(OL) or very high resistance,If it is enough to make you continuity alarm ring we might have a problem ,maybe not. Some meters are much more sensitive than others.If it shows no continuity, between each leg(Yellow wire) from the stator it has passed the first hurdle for sure,your stator is not grounded to frame.

Next set your meter to VAC,200 or less.Remember I mentioned AC output,we are now going to test that.Start the bike ( you should have the battery fully charged before testing your charging system BTW) warm up the engine to normal operating temperature. This next part is easier with a helper,but you can do it by yourself.run the engine up to around 3K RPM's and check between any and all combinations of the three leads from the stator,you should have between 40 to 70 VAC .Is the voltage up to snuff ? It may be a little more but it's doubtful unless you have one that has been rewound as heavy duty or high output.Did it pass the test?In order to pass it must have proper voltage between all combinations of A1,A2 and A3,if one combination is very low or no voltage at all you have a bad stator.If it is good ,time to move on.

If it passed the voltage test ,shut down your engine and perform the resistance test you did before you started the engine.Has any thing changed between each stator leg and the engine case? Is it still showing OL or a really high resistance reading?If so your stator is good.Feel very relieved about now.

If not it and it is showing a low resistance reading to the engine ground this is not good,Your stator is probably going to ground when warm.

Is every thing up to par so far.If so your life just got easier.Plug your stator back up or cut those nasty bullet connectors off and solder those wires together and heat shrink them so you don't have to worry about a loose or weak connection there any more.I will note there are some folks who put fuses in those connections.I personally don't like that Idea but its your bike,If they are fused and something down stream from there grounds it can take out one of those fuses and you are running on two legs of a three phase system and loading them even more,which raises the heat in the stator and I believe it can lead to stator failure,JMO ,do what you want.

Now,we are ready to move on,to checking the R/R out put.Time to go to the DC scale on your meter.You do have the seat off don't you? If not take it off now.Check Battery Voltage directly on the battery posts.If your battery is good and charged it should read close to 13 volts.Contrary to popular belief a a 12 V battery that reads 12 VDC is Dead! Charge it up it should read 12.6 or above when fully charged at rest.If it won't charge up or won't hold charge overnight ,you just found your problem.If it needs charging take it out of the bike or at least unhook it from the bike's electrical system to isolate it and test while disconnected.if you have to charge it.Go in the house and do whatever it is you do while not riding and come back later and test the battery voltage.Is it good? Reconnect it.

Now start your bike and warm it up again if you had to let it sit long enough to cool off.Check battery voltage at idle.It may be the same as before or a little less, most unmodified VN7XX's don't charge much if any at idle.with your leads attached to the battery posts run the engine up to around three K rpm's again.At this rpm the charging system should be putting out around 13.6 VDC or so.Are you getting this much voltage.I hope so and your charging system is doing what is supposed to,If not lets move on.

A common problem is a bad connection on the R/R plug.Now it gets fun,if you haven't relocated your R/R it is underneath the battery box and directly over the Goats Belly,so take your left side cover off and see if you can see it.Unplug it and check the terminals on the R/R and its plug on the wiring harness.Check closely,if they are corroded clean them up and I mean, shiny and clean,both sides of the connections.If you cleaned them up good put a little dielectric grease on them and reconnect it.Back to the battery and your voltages.Check them again just like you did before and and see if they are the same .If they are you have a bad R/R or wiring issues and it is time to check the wiring and connections including all the frame and engine grounds,I'll let you go through all that mess alone,you're gonna be a while.

Did the voltage come up to the magic 13+ when revved up ?You fixed it!!! Now go ride!!!
If not start checking the connections and if you clean all the connections and see no improvements It is R/R time.

It is that simple,you can test the R/R values found in the repair manual or in the online manual on here.Let me stress that the R/R readings can be within range and it may still not charge.This why I tell you to check ALL connections before you buy a R/R,it is worth your time even if this not the problem even if you find a bad connection on the R/R .You will enjoy a lot more trouble free miles of riding.

I hope this helps simplify trouble shooting your charging system.I am a firm believer in "start at the start". It all starts with the stator and if it isn't right,the rest doesn't matter.So by all means Check it and the Connectors coming from it FIRST!!! It may save you a bunch of time and grief.

I know this a long post but I would imagine you can do these tests faster than I typed this.
It really is that simple :smiley_th
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What's the big benefit of the Tuxedo mod? That you don't have to remove or tilt the engine to replace the stator?
I tried reaching out to the guy on this forum (Tim?) that rebuilds them, but he's not around and his website is down. What do you recommend for a stator replacement? EBay?
Im trying to test my charging system.
To test I unplugged the R/R my pulling this connector off of it:
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Then I attempted to locate the bullet plugs. I think these are the right wires, behind the Vulcan vanity plate, coming up from the underside of the bike and connecting to the the wiring harness, but they aremt bullet plugs at all. what do you call these? Maybe they are bullets but theyre too dirty.
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So i tried testing those three wires by unplugging the R/R, setting the meter to ohms at 2k (200 was my only other option down from that), and touching the other lead to the engine along one of the cylinders:
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I didn’t really understand the readings. When I saw “1” I turned the meter down, as in when it was reading 1 on 2K, I turned it to 200. Then I was getting readings like 20 or 30 on a couple of them. What should I be seeing?
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Here’s my meter. Set to ohms 200 here’s what I get (with the RR unplugged):
Each wire to engine block: they all start high and start settling around 1.8 but then slowly tick down to 1.5 or so as I sit there.
Battery negative to the same spot on the engine: starts around 1.2 and slowly ticks down to 0.9
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Can you elaborate on why you're saying that and thereby educate me?
When I set the meter to 200 ohms, the same as I've been doing on the bike, it reads the same as the bike, and as the battery: 1.5 or so which ticks down to 1.2 or so.
If the same resistance shows on the multimeter when I touch the leads as when I test any other circuit, the multimeter must be bad, or I can assume there's the same amount of resistance in all the scenarios?
I hate to crowd this thread with trial and error. It's such a helpful thread. I will get a better multimeter that at least passes a resistance test and I will test again.
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