Help! New biker and something is wrong with the charging system?!

[Guest]

Hello!

So I did an oil change and overfilled it a little. Drained some oil out to what I think is the correct level according to the manual. I left my lights on and the battery didn't have enough juice to start the bike. Charged the battery over night and the next day it worked perfectly while going to work. When leaving work, at night with the headlights on, the bike died on a highway speed road. I twisted the throttle and got sputters then it died out. I kicked it over since the starter wasn't working again. Got to my location and the bike died at a stop sign. Kicked the bike over a couple hours later and rode it for literally 1 minute before it died again. Now it can't be kicked over and the lights on the bike is dying. I for sure have a dead battery. Do you think something is wrong with the stator or r/r? The guy I bought it from said he just changed those but didn't change the battery after frying the r/r in the past. Just bought a new battery and i'm going to try it out tomorrow but any thoughts on if I need to buy a new stator or r/r? Thanks! btw, I have a 78 gs750.

[mosespyi]

Also, this is my first bike and I'm very new to everything. Mechanically inclined but electric systems are not my thing.

[tom203]

Welcome to the fun.... Do the Quick test in this link and report all 6 results. Note that you need to start with a fully charged battery

http://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST/page2&p=1272192#post1272192

[phydeauxmutt]

Your bike came from the factory with separte rectifier and regulator. Newer bikes (starting in '80) had them combined into one unit. If either one of yours is faulty, it is highly recommended that you replace both units with a newer combined unit. The current favorite of the forum is an SH775 unit that comes stock on Polaris side-by-side ATVs. Prices on new units have taken a hike recently, but used ones can be found on eBay for under $50, but you have to know what to look for.

Although replacement is not a bad idea, there is no need to spend money until you KNOW that you need it, so do the testing that tom203 suggested first.

[Redman]

Welcome to the forum.

If it starts with a new battery... then you can suspect the charging system not working..... but you already somewhat know that because it started after having it on a charger. So maybe you dont really need a new battery (but if it is old, or unknown may need one sometime soon anyway).

What you really need is a voltmeter (multi meter) to check the charging system, the quick test mentioned by others. And then will also need the meter to trouble shoot the charging system.




.

[mosespyi]

so just checked finally and started with 12.9v with key off. basically started it up and warmed it up and the volts never went up. revved to 5000 rpm and still the same voltage. afterwards the battery tested 12.4v. start with r/r?

[posplayr]

so just checked finally and started with 12.9v with key off. basically started it up and warmed it up and the volts never went up. revved to 5000 rpm and still the same voltage. afterwards the battery tested 12.4v. start with r/r?

OK then do the Phase B Stator tests. Make sure you do the leg to ground as well as they are most important and you can ignore any involving an ohm meter.

http://www.thegsresources.com/statorpapers4.php

[tom203]

Just in case this gets overwhelming...

Disconnect stator leads from r/r. with your multimeter set on 200vac scale (or same scale that you would use for house outlet) While running bike to about 4k to 5k rpms, measure stator lead to stator lead and note the 3 readings. At same time and same meter scale, put one meter probe on any stator lead and other probe on good bike ground - you want to see a very low voltage reading, 0 would be best.

[Redman]

Mose, if you are still here,
just to clarify something

THis is one test, measure 3 voltages, should be about 70vac
... While running bike to about 4k to 5k rpms, measure stator lead to stator lead and note the 3 readings. ...

And this is another test, measure 3 voltages, should be about nothing
... At same time and same meter scale, put one meter probe on any stator lead and other probe on good bike ground - you want to see a very low voltage reading, 0 would be best.