Newbie trying to figure out charging issue

[ebuzz67]

I'm not really a mechanic, but, just got 1977 xs400 cafe back from shop about month ago, had a starter (solenoid, clutch, etc.) installed along with a lithium 4 cell battery rated for 400cc. I noticed about every 4 days the light cluster is dim and it won't crank (solenoid clicks) so i put a trickle on it and away it goes for another few days, then same thing - put a multimeter on it and only pushing about v12.3 when running.....

I pulled off the regulator to increase voltage (found advice in forum) but no adjustment screw, so I just bent the piece of metal closer to the coil and get about v12.9 but nowhere near the 13-14 volts it should be.

Wadda you think? Have the alternator rebuilt? I'm seriously not that inclined to mess with anything else cause afraid of messing it up further...

or worse case scenario just throw the trickle on it every few days...

 

[kindest]

even when you rev the engine and check with multimeter it's at 12.9 or are you talking just idling.

 

[ebuzz67]

weird thing, today i checked voltage at idle and was showing between 12.9 - 13 volts but when I rev over 3-4K it fluctuates between 12.94 - 12.99

I spoke with my mechanic and he will investigate this weekend - my question: If it is showing between 12.9-13 is it charging the battery at all?

many thanks!!

 

[kindest]

well if your battery fully charged is under 12.94 then yes it's charging
It's supposed to show 14v+ when you rev 5,000 rpm so if it doesn't then I would say something isn't working right.

 

[arfstrom]

Our bikes are strongly known to be 30 years old. With that, Quite a few of us have replaced quite a bit of stuff. 1 st off, I recommend follow the manual, which is downloadable from this web page, (The Garage), 2. Pull off the left side panel, Seat, eveything your looking for will be here, or under the battery box. 3. per the manual multimeter test the 3 white wires, record the numbers. The stator is on the left side, the 2 sets of wires from under the rear engine heading up to the top of the battery box, has a jumper wire that goes from there, to the rear of the battery box, and then then the connecters there, are connected to the Voltage regulator, and the Recitfier. Yup test all them out, and while your at it, after you get the first set of numbers for the white wires, feel the bottom of the engine, where those wires leave the engine, and then are attached to the back of the engine, heading up to the battery box. See if those wires feel toasted, brittle, like every touch its falling apart. (This is what I think the problem is, but I want to use a systemmatic approach, get numbers, and after you touch those wires, see if they have fallen. Ultimately I think my original rectifier is good, I needed a new Voltage regulator/ and re-wire project. So My last recommendation for the night is go though Drewpy re-wire project. Its on the Homepage, and under Tech, under Electrical Re-Wire...Highly recommend reading this. How ever if I am wrong, sorry. good luck