Gsx r 750 1998. Battery holds charge when riding with lights off. But not with lights on. Stator or rect/reg??

Did you check the rectifier/regulator? AC Power comes from the stator via the reg/rect which converts it to DC volts and sends it to the battery.

Find the reg/rect. check the AC voltage going in, should be about 18-26v & 3000RPM. If you have voltage check the out put Red and frame should be above battery voltage.If not turn off engine and check voltage at reg/rect Red wire (+) and Black(-) if fitted could be conected through body to frame..It should be at battery voltage.if not check for burnt or dirty conectors on the red lead and or the black lead if fitted or the mounting bolt for the reg/rect.
If you have battery voltage and AC voltage at the reg/rect suspect the reg/rect. some units have an extra wire that can be an ignition feed that has power on it when the key is on, but sure these dont have it.

If you dont have AC voltage check the (usualy) yellow wire some can have 1 or 2 wires. If it has 2 wire check voltage across both, if it only has one check yellow and the frame.

check your charging systems. your reg/rec may be bad or you stator. when you start your bike you should get 12.5 or so when reved should get 13.5 to 14.5
Mark

Hi
As the battery & regulator/rectifier have been replaced, the only other things to check are :-
Continuity from reg/rect red wire to battery & to earth, then check for continuity between each of the 3 yellow wires, all should be the same resistance - if not the stator coils in the alternator are faulty

Ride safe
Bike-Doc
Please mark this as very helpful (if it has been!!)

You have a bad stator, or rect/reg. Take it to a shop and ask them to check your charging system at the battery. If it does not go over 12.5+ volts they need to check the stator output. If the stator is good, replace the rect/reg. Chaz Moto DC

This is probably due to a faulty wiring, regulator/rectifier or, less likely faulty alternator
1st check the wiring & connections from the alternator to the reg/rect (3 yellows) then check wiring to the battery (thick red)
You should get 13.5 volts (with a fully charged battery) across the battery terminals rising with the engine revs to no more than 15.5 volts, if its over then the regulator is at fault
check the alternator for continuity between the 3 yellow wires (3 pairs) at the reg/rect plug after disconnecting it. the 3 pairs should have a similar reading & none should go to earth
To check the rectifier part you need a diode drop setting on your multimeter. there should be a reading 1 way only between the red & any yellow and between the black & any yellow if not it will need renewing

Hope this helps
Please mark as helpful if it has been
Ride safe
Bike-doc

You have two components for the charging systems. Stator and Rectifier regulator. As a rule of thumb we always change both. First you need to confirm that the outboard is not charging your batteries. use a battery load tester on your batteries confirm you have no dead cells. Second with a fully charged battery, multi-meter, and a water hose connected to your outboard cooling system. third for a picture and diagram of the ignition system go to www.yamaha-motor.com. click on outboard motors,parts and service, view parts catalog. find your year make and model by following steps listed at top. search electrical 1,2,3 until you find a RECTIFIER & REGULATOR ASSY. Click on generator to find the stator. when you find it you will have a picture reference. Check for good ground at the Rect/reg. the stator creates AC voltage the rect/reg converts to DC. rect/reg conects to the battery to charge it through a solenoid on the engine. Connect your multimeter to this solenoid to get the true reading from charging system. start engine check voltage through all rpm ranges. 13.5 v thru 15 v. The other troubleshooting test and disasembly will require a Manual. also to remove the stator you'll have to remove the flywheel.Clymer Service manuals are available through your local outboard dealer. good luck

I have a '07 C90T.
I have just replaced my stator. I replaced the reg/rectifier earlier this year. I replaced the battery one year ago in October.

I firmly believe what started the problem. Two guys that I told I didn't need help, but they pressured me to let them help. They hooked a battery backwards to my bike. A lot of people believe that's what shortened the life of the rectifier and stator.

But keep this in mind. The connections for the regulator/rectifier are not waterproof. I had done a lot of rainy riding and I first found a burnt connector on the discharge side of the reg/rect. My mechanic told me I needed to replace the reg/rect so I did but I soldered the wires and made them waterproof. I didn't do this on the stator side of the reg/rect and a few months later, when the bike quit charging again, I found that connector burnt, so I cut it out and soldered and waterproofed it.

Two days after we got back from a 700 mile round trip to Red River, NM, my bike quit charging again. This time though, I have a voltage meter on the bike, so I was aware of the problem before the bike could strand me someplace. Get one of those btw.
When I checked the old stator after I replaced it, I found the stator good but the pulse signal generator bad. It's required that you replace both btw. You have to, they are joined at the grommet.

Ok well, the battery cost $60 last year and I replaced it myself.
The reg/rect cost $140 through my mechanic and I replaced it myself.
Got the stator online for $173 shipped and they advertise a better stator that puts out 20% more power.
Not counting little things like solder, tape, heatshrink and such, I'm out a little less than $375 on my charging system.
I hope it's a done deal.
Again, some think the problems began when the battery was hooked up wrong, but I lean to believe the sub-standard Suzuki connections may have a hand in this.
Hope this helps. . . Joe

Stupid Question but are all your wires clean and tight connections? Also make sure your batt ground is good too. R1's can be picky like that.

Sincerely,

JC

Sound like he has a charging system problem . I would check stator output. If that checks good then it's the regulator.

I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_5bac37c3cb991fdb