Topic: CB750 K6 Charging not charging

[bigvalyeti]

Hello guys,

I am starting to loose faith with my CB... 
I bought this bike a few years back never really got the chance to ride for long trips as I quickly experienced engine problems.
I decided to have the engine fully redone by Gabriel Martin Garage in Longueuil, Canada (Honda parts only).
That done the engine runs like a charm. Only big problem is the charging system. When I bought the bike it was already running a small
8 cell Antigravity battery with a mofset reg/rec. My mechanic doesn't really know what's not "original" so he doesn't really want to understand lithium technology.
Here are all the mods/tweaks made on the bike:
- Dyna S + dyna 3 Ohms coils (with proper insulated cables and boots)
- Cognito Moto oil tank + air filter (carbs all rejetted)
- Antigravity 1201 battery
- Ricks motorsport lithium compatible (field coil compatible) Reg/Rec - directly connected to positive battery terminal through a relay.
- Delkevic straight 4 in 1 exhaust
- Daytona Velona W speedo/tachometer
- H4 LED main light
- Purpose Built dual light turn signals
- My mechanic redid the wiring harness (not 100% trusted...)

First problem while reassembling the bike my mechanic couldn't have the bike go over 13.5V even when revving it up around 3-4k rpms.
He blamed the bike because as always with him "its not original!", I agree but I am a stubborn person.
Turned out one of the phase of the stator was not connected (-___-") Problem fixed! I rechecked and the bike was well stabilizing the voltage at 14V-14.2V after revving it.

So I decided to go for some test ride around town and first trip 50k away, no issue, bike is staying around 14V on the highway.
Second test ride 160km away, one way no issue everything is perfect. On the way back my lights start getting dimmer and dimmer until the whole bike dies.
Checked the battery almost at 10V.
Got stranded.. Again...

I suspect the Reg/Rec or the Field coil to have failed.
I checked the stator and 6 Ohms on each phase cable and no ground either.
I recharged my lithium battery and tested again, no charge at all, bike voltage maxes out at 13.5V, the voltage from the Reg cable going to the field coil stays at 13.3V and weirdly goes up a bit around 13.5V when I rev the bike (should theoretically go down as I rev, right?).
My field coil gives me 8 Ohms resistance, but my Stator output between each phase doesn't go higher than 13.5 V AC.....

Has anybody ever experienced that?
I am starting to seriously doubt a fully working/reliable lithium conversion is possible...

[scottly]

I've been using LiFe batteries since 2011.
How was the bike harness rewired? How is the regulator connected to the battery + terminal with a relay? Are you sure you haven't lost connection to a stator phase again?

[bigvalyeti]

I knew it was possible...

Any idea what I could have gone wrong in my setup?

I think for the rewiring, my mechanic bought a new harness and reconnected everything on ther.
Regarding the regulator, instead of connecting the black cable (sensing wire) to the harness, he connected it to a relay and then the battery positive terminal. Like that when ignition key is on, the reg only reads what’s at battery

[scottly]

If you have 13.2v coming out of the reg on the white field coil wire, and the battery reads 13.5v, it means the reg is calling for full charge, and if the field has the green wire grounded like normal, then it would point to the stator. With the white field wire disconnected from the regulator, measure the resistance from the field wire to the battery negative terminal. It should be about 7 ohms. Also, if the wiring has been modified for the Rick's reg/rect, a common mistake is to just connect the field green wire to the reg green wire, instead of connecting both to ground.

[bryanj]

Age old check is when ignition on does the generator casing get magnetic?

Sounds like the wiring to field coil is suspect to me as all the 3 pairs of yellows you say have tested good.
In 40+ years i have never seen a field coil fail and only stators damaged byaccidents.

One other possibility is has the rotor come loose on the crank

[bigvalyeti]

Hello again,

So I tried to run the few tests you guys recommended.
- No magnetism on case when ignition is on.
- I have 7.2 Ohms from field coil to battery negative terminal
- I checked and both wires (field green wire and reg green wire) are connected to ground.
- Rechecked Ac wires and I got .5 Ohms between all of them.

I am taking off the wiring harness right now to check it

[scottly]

Wait. How did you check for magnetism? The three screws that hold the field coil inside the alternator cover are what gets magnetized.

[bigvalyeti]

I put a 1 CAD coin on this spot and it didnt stick, Should have I put it exactly on the bolts?
Just with the ignition on, no engine running ?

[scottly]

Also, the Dyna ignition system draws more current than the points due to increased dwell time, and the 3 ohm coils draw more power than the stock 5 ohm coils, even with the points, so having both places a considerable increase in demand on the charging system. In fact, Dyna does not recommend using the 3 ohm coils with these bikes.

[scottly]

I put a 1 CAD coin on this spot and it didnt stick, Should have I put it exactly on the bolts?
Just with the ignition on, no engine running ?

Are Canadian coins made from steel?? Yes, you check directly at the head of the bolts, and yes, just the ignition on, no engine running.

[bigvalyeti]

Yeah they are.
Mmmm so could it be the combo 3 Ohms coils + Dyna S pulling too much current from the charging system ?
I replaced the main light for a LED (H4 style obviously) these are the only main things drawing current.
But thats weird, I have a voltage wire on my Speedo that indicates me voltage while im riding and I could clearly see 14+ on the highway. If it wasnt producing enough current I wouldnt have such voltage readings?

[scottly]

I didn't mention the coils before because you said that after fixing the missing phase the system was putting out 14V. Perhaps the battery is somewhat discharged, and the charging system doesn't have enough power left over to charge it back up quickly; it may take some time to increase to 14V?

[scottly]

Does your headlight have an on/off switch or is it always on? If it is always on, try removing the headlight fuse and see if the voltage goes up. Also, if you use the electric starter, it draws a fair amount of power from the battery that needs to be replaced.

[bigvalyeti]

I doubt that , when I reconnected the missing phase I had recharged the battery (with proper lithium charger) and even at 2k rpms the voltage would stabilize at 14.2V easily.

Now after that unsuccessful  "long" ride, the system is capped at 13.3-13.5V with battery also fully charged at home the night before

My headlight is always on yes, and I checked today with the electric starter (cranking) battery voltage went from 13.5V to 12.5V then went back up to 13.3V while idling

[scottly]

Remove the 7 amp headlight fuse and see if it makes any difference.

[bigvalyeti]

Okay so removing the light didn't change anything, BUT
I disconnected the regulator part of the RR and connected the the filed coil (isolated type) wires (white and green) to the battery directly with jumper wires with a 5 amp fuse.
The moment I connected it, my one Canadian dollar coin was indeed sticking on the case screws. I then measured the stator AC output and i did have a good 30V at idle going up to 50+ revving.
So I mean my rotor/field coil and stator should be fine, right? The culprit is then the RR...
Do you think it could have started to fail when my mechanic forgot to connect one of the three stator phase cable? ( he did tested the charging system like that many times / also switching with an AGM battery / and a rode the thing back 20km back to my place like that).
I noticed, when I was riding at higher speed, my tachometer needle getting crazy at around 4-5k rpms, so maybe the damage done to the RR was only getting visible and had worsen under heavier load.
My tacho/speedo also give me the battery voltage from a point on the wiring harness, so like with a lil difference but at higher speeds, it would always fluctuate pretty fast between 13.5-14.5V like crazy.
Could this be AC leakage from the RR?
Would it be possible for it to fail due to the vibrations of the bike while riding for extended time at 5k rpms?
So many questions...

[scottly]

If you have 13.2v coming out of the reg on the white field coil wire, and the battery reads 13.5v, it means the reg is calling for full charge, and if the field has the green wire grounded like normal, then it would point to the stator.

When you had 13.2 volts ongoing to the white field coil wire, it would have been the same as jumping the white field wire to battery plus, and you also measured the correct resistance from the white wire to battery neg, so you should have had magnetism. Since the voltage was jumping around, I would suspect an intermittent  connection either on the white field to white reg or the field green to ground. With the key on, and headlight on, measure the voltage from the battery negative post to the head of an screw on the engine, and then to the green field wire: it should be zero in both cases.

[bigvalyeti]

Yeah I can try that, only suspect thing is I did reconnect the RR fully and noticed the coin was still magnetized (ignition on). BUT when I measured AC voltage on the stator cables (everything connected) I only had 12-13V at idle and no voltage increase when revving. This would mean my RR is dead right?

[scottly]

Is the reg putting voltage out on the white wire?

[bigvalyeti]

yes

[scottly]

With the engine running is still putting out voltage? Is the field still magnetized?

[scottly]

Is the problem with the relay???

[bigvalyeti]

Yes engine running still magnetized but when i inserted my multimeter in the connector, AC voltage wouldnt budge,
For the relay it was probing same voltage as the battery.
Should I jiggle these parts and check if voltage goes up and down...

[scottly]

Connect the black reg wire directly to the battery plus terminal, bypassing the relay.

[bigvalyeti]

I'll try all these things tomorrow, thanks a lot!