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4 Posts
Discussion Starter · #1 ·
I recently acquired a 1992 VN750. It starts up fine with a freshly charged battery, runs strong for about an hour, and then dies. At this point I have to take the battery out, take the bus home, and get a freshly charged battery. The bike starts up perfectly with the new battery and the the cycle repeats.

I'm not much of a biker; as a layman it appears to me that the engine is not charging the battery and the bike's lights etc. drain the battery.

What could be wrong? How do I identify the problem? I can poke around with a multimeter if someone points me in the right direction. I wish the electricals were as solid as the rest of the bike.

(Both my batteries are Yuosa MF, but that doesn't matter here)

Search Goddess
2,002 Posts
First check your connections and ground to make sure they are all clean and solid
then the R/R
From the yahoo vn750 group Files..
From: "Dan Morgan" <[email protected]>
Date: Thu May 29, 2003 1:42 am
Subject: Re: [VN750] Electircal 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
2K VN750
VROC #9566
Altus, OK

then the stator

"You can determine if your stator is bad without
too much trouble, it should take about 5 minutes max.

Unplug and test the three yellow stator wires;
they should be .34 to .52 ohms between any
combination of the yellow wires, with no shorts to

4 Posts
Discussion Starter · #3 ·
Thanks for your response, Dianna! I finally got the time to test the bike and
it turns out that the stator is in fact the problem. I'm thinking of ordering an
Electrex stator, the one that claims to generate "30% more" than the stock stator.

Will the stock R/R be able to deal with the extra output? Or do I have to
order another R/R? I might order Electrex's regular stator (without the
extra 30% ) if it's going to be an issue. The labor costs for the stator's
replacement are going to burn a hole in my pocket and I'd like to save as
much as I can on parts. Any thoughts?

Search Goddess
2,002 Posts
It was my understanding that with the newer and improved stator, you also needed the newer R/R but Electrex should be able to verify that.
As far as labor costs.. Do you have a place where you could do it yourself?
I replaced my stator. There are instructions for the engine "tilt" in order to gain access to the stator cover (You need clearance to pull it out away from the shifter shaft)
If that is a possiblity and you have a weekend. It could save you a bunch of Dealer labor costs. I'd be able to repost them. (they were previously posted in an engine pull post)

According to the electrex site..

RR60 - Single phase RR goes with OEM stator.

RR37 - Three phase RR goes with OEM three phase...

4 Posts
Discussion Starter · #5 ·
stator is weak, not fully toast

I lack the skills, time, and space to replace the stator myself. So I'll have to get it done at the dealer's. :( He tested it and said the stator is weak. It's generating only 40V AC at 4000 rpm when it should generate almost double that. Even with 40V AC input the R/R is unable to generate enough to keep the battery happy. Hmmmm.

Where can I find the normal output voltage of the alternator at various rpms? It's not in the service manual. The DC out from the R/R should be 12-15V (going up with the rpm) but what about the AC out from the alternator?
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