Need jump to start, but runs GREAT? Acts like this only when warm

[redsoxvw]

Hello....I have a couple of questions about some electrical gremlins on my 1980 gs750.....This GS is new to me, and was test riding the other day(feeling for bugs that need tending) and all was good (Minus a sticking rear caliper)

I just purchased a new battery for the bike, installed it.....I bled the brakes and seemed to have the rear caliper free, so I proceed to test drive.

Now when I shut the bike down, I cant start her up unless I use the Jump pack.....So Im assuming a charging issue, but as soon as it starts I take the jump pack off, and the bike runs flawless, nice and crisp no hesitation at all.....

I figure a charging issue would give me a sputter or something, the lights stays bright etc....

Another thing, I noticed It only acts like this after shes warmed up???If I let it sit all night, It will crank when I hit the starter button.....No dice after its warm though........

I also noticed my tail light only comes on when the brake is applied, but no running light.

I am in the process of reading "The stator papers" I was just hoping to maybe get some quick tips or comments from the more Seasoned GS folks on here, as Some nice weather is heading my way this weekend and would love to enjoy it.....

Thanks in advance for any and all input. Its appreciated

PS...You know the saying when it rains it pours......Well during the last test run today, I got caught in a down pour and the bake caliper was locking up something fierce...Made for an interesting last couple minutes

[Big T]

First, do the basic test in the Stator papers

1. Test battery voltage not running
2, Start bike, test voltage at idle
3. Rev bike to 3000 rpm, test voltage

report your results

[almarconi]

If you haven't done it yet, start from the headlight bucket and work your way to the taillight. Disconnect and clean every connection and ground.
It is highly possible that you've got a corroded connection somewhere that is causing your problems.

[BassCliff]

Hi,

More troubleshooting is necessary. Go through the Stator Papers to eliminate or confirm any charging issues.

You could simply have a bad light bulb in your tail light. Frequently only one filament will burn out in a dual-filament bulb.

Possible heat-sensitive components are the coils and igniter. You may need to clean up and install new brushes in your starter. The starter clutch could be giving you grief. Download a manual from my site and check the troubleshooting procedures. Check my website's 'Odds and Ends' electrical section for 'Diagnosing Slow Cranking'.

Thank you for your indulgence,

BassCliff

[redsoxvw]

Just an update, I was going threw the stator papers, and was using the diagnostic chart, and Im coming up with

Bad connection in the positive lead from RR to battery(+). Check the entire lead (suspect the connectors as well as the fuse-box and fuses). Good connections are extremely important in this high current lead. Solve the problem and return to START

Ok Im pretty sure my RR is not original, It has 3 yellow one black and one red wire running out of it...(And a cpu fan mounted to it).....the red lead, goes into the wiring harness and runs up the front of the bike. Could any one point me in the direction of a schematic for this wire?????...Thanks in advance for any and all input

[Big T]

Go to Basscliif's website, he probably has a manual for your bike