'79 XS11F charging troubles

[W1BV]

Hello all - having a spot of trouble with my charging system and am unsure how to proceed, Alternator resistances within spec - but battery stays at ~10.5V while engine running and/or revved a bit. Once shut down - battery returns to ~11.75V. Top off battery to ~12.5V and repeat.

Any ideas where to go from here?

Thanks for reading - Mike in MA

[Bax]

Hi Mike, The charging system needs to be excited to output. First guesses would be the connector or the voltage reg/rectifier unit. Check out geezer's store for an updated unit if the pins in the connectors are visually fine.

http://www.oregonmotorcycleparts.com/Reg_rec_units.html


Bax.

BTW: I'm living in NH and work in Wilmington, MA.

[DiverRay]

Also, please check the large white connector BEHIND the fuse panel! They get old, and then cause heat from the resistance and burn up. This is the main connector for the charging system.
#2 check, take the mount screw with all the wires on it off of the reg/rec, clean up the screw/wires, and tighten down. without a ground the system will not work.
Geezers site, oregonmotorcycleparts.com, also has a good trouble-shooting section. do read through it for help as well.

[W1BV]

Hey Bax - greetings from Peabody! The PO wired a lot of the bike from scratch (it seems) connectors look clean and whole. I actually bought a cheap reg/rec from the 'bay in trying to get to the bottom of a different issue - which I've since debugged - so haven't tried installing it yet. Perhaps I should. Appreciate the response!

Thank you as well Ray - will give it all another once over and check out Geezer's as well. Just noticed your signature - 73!

Will update with anything interesting!

[W1BV]

Turns out it was the reg/rec - seems to be charging now - glad I had that spare. Thanks all!

[cajun31]

A little late to the show but like Bax said they don't charge until they get excited. Meaning you have to rev the bike up to I believe 2000 rpm in order to see a voltage rise out of the reg/rect. Of course the best thing to be able to do is to get out and ride it. I hooked up a voltage meter inline with mine so that I can glance down at it while riding to see if everything is elevated as it should be when riding.

[W1BV]

Going to try one of Geezer's units. Took her out yesterday and after idling at a couple stop lights, she died at one. Waited 5-10 minutes and was able to get back down the road a bit before she finally really died. Got a decent workout pushing her home though. It started raining, of course... but we had a nice double rainbow - so all was well.



Thanks again for the replies!

[bikerphil]

If you want to temporarily increase the charging output, tap into the green field core wire and ground it, check with a meter, should be 14+ volts with a rev. of the engine. It shouldn't harm anything doing this.

[cajun31]

Definitely sounds like your voltage regulator rectifier has bit the dust.

[DiverRay]

If you want to temporarily increase the charging output, tap into the green field core wire and ground it, check with a meter, should be 14+ volts with a rev. of the engine. It shouldn't harm anything doing this.

I would only do this as a quick test of the rest of the system!! It WILL kill your battery if you try to run it this way! I know this for a fact, thanks to a shorted wire in the loom. It will also get up to about 15.8-16.2V at higher RPM.
But again, this IS a good, easy test of everything in the system short of the reg/rec. You should be getting about 15V at 2500 rpm.

[W1BV]

At the moment, voltage drops steadily at idle, and creeps up a bit when revving... going to try the Geezer unit and hope it does the trick. Thanks again to all for replying.