85 xj700 maxim will not charge while running

wife's 85 Yamaha xj700x, ran rough and needed full choke to start and run; clean carbs and swapped out old fuel solved that. it ran so good, however.

now bike will start up and run perfect for about 20 mins on the road strong and clean then suddenly stall out and not restart. replaced the older battery, same.

investigated with a multimeter found battery not getting recharged during operation, but soon as I shutoff the bike the battery goes straight back to steady 12+v.
I've checked grounds, connections, battery has been tested and is all good, no shorts or ground outs.

i multimeter tested stator, rotor and rectifier; all pasted voltmeter testing. still bought new stator, and rectifier and installed ran for a bit really strong then died, still not getting recharged during operation.

took bike with new stator and rectifier installed along with the new rotor and old parts to car mech that also rides mc and does most of his own work. he ran into the same issues. he's tried all the combinations of new and used parts, and even put in all brand new connectors just to be safe. still no dice

anyone got some advice. need to get my wife back on the bike

 

Are your alternators carbon brushes in good condition? The alternator does not charge the battery until about 2000 rpm and above. Do you have the factory fuse box? That should be changed for a blade fusebox.

 

Check the fuses after it stalls out. Make sure no e of them are hot (10 or 20 amps at operating voltage can get pretty hot!)

Sounds like a heat related issue causing excessive power draw on one of the circuits. Once the electrical system gets down to 10v or less, the TCI output transistors will not operate properly.

 

I had the same problem with my 85 XJ700N. Output was so weak that sometimes just hitting the brake would stall it. It was the brushes. Replace and all is good.

 

Yes l think it's the brushes. Put the multimeter set to 20v on the terminals on the battery with the engine running see if you have approximately 14.7 if that's the right output volts above 2000 rpm so the alternator is in the operating range.

 

The 700X will have a single main glass fuse under the seat, and then some blade fuses in the instrument cluster - not the old-timey box with a bunch of glass fuses in it.

 

thanks for all the replies, once i get the bike back to my place ill go through these suggestions and post an update then. much appreciation