1972 CB450K5 Poor Charging

RobMan

RobMan

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After taking my recently restored 1972 CB450 on a fairly long maiden ride (80 miles) and it ran great until the last couple of miles when it started trying to stall. Subsequent troubleshooting leads me to believe poor charging and a ran down battery was the problem. I initially thought the halogen headlight bulb and incandescent taillight bulb were the main culprits as with the lights off the battery voltage would go to over 14 volts at 3K to 4K rpm but following advice from @stl360+450 to do a AC check of the stator I believe I have a bad unit. Also thanks to @stl360+450 for the link to @66Sprint's lecture on this subject, good stuff!

Electrical 101...Lecture #4...Testing The Alternator

Unplug the alternator output wires from the main harness...... With a multi-meter (or other means) FIRST verify that none of the three output wires (Pink, Yellow, and White) are contiguous to the engine case...... They SHOULD show continuity to each other (although with varying amounts of...
www.vintagehondatwins.com www.vintagehondatwins.com

This the readings I got:

Stator coils ground check tested good with no reading to ground.

Ohm check between coils could not find specs in FSM.
yellow-white 1.5
white-pink 0.7
yellow-pink 1.1

AC volt check at idle and 3K-4K.

white-pink
idle 15.9
4K 41.9

pink-yellow
idle 16.9
4K 40.9

yellow-white
idle 0.2
3K 0.6

According to @66Sprint's tutorial on this subject the the VAC check for the Yellow-white pair should be 3 to 6 VAC and I am only getting less than 1.

There is a problem with the stator but before calling it bad I need to pull it and check the wiring coming off it to the connector which I had replaced due to the old wires being faded faded and hardened by heat.

Drained the oil today but had other chores so will try get the stator removed later this week. More to come.
 
After doing some more research and reading another post from @66Sprint I have decided to hold off pulling the stator and try it out for awhile with the LED bulbs and see if the battery stays charged. The only issue I was having was with the yellow-white pair and in the other post on a CB350 he said:

66Sprint said:
Those AC output readings are fine (about normal where it counts)......
You only need to be concerned with Pink to white (14VAC) and Pink to Yellow (17VAC).....
The low reading (White to Yellow) is the differential between the parallel sets and while usually 4 to 6VAC is relatively meaningless as to charging.....
Click to expand...

Hopefully give it a good run this weekend and report how it does.
 
Notice there is a larger difference between the parallel circuits in the quoted text. Yours were very close together, so I would agree with your assessment that the stator is likely good.
 
I agree that the stator looks good. The pink wire is the common point, and the yellow and white should be nearly identical in Voltage relative to pink, White provides about twice the total current, therefore should have about half the resistance to pink as white to pink. Few common Ohmmeters measure accurately at that low a value, but the readings do track in the right direction.

Just how many Watts is your headlamp? Stock is 25L and 35H, and the charging system barely breaks even at about 1300-1500 rpm with that. A 100W headlamp would mostly stop charging at any rpm.
 
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Headlight was a 65/55 halogen but has been replaced with a LED which from what I can tell uses 22 watts of power. I have ab LED taillight bulb but haven't installed it yet.
 
RobMan said:
After taking my recently restored 1972 CB450 on a fairly long maiden ride (80 miles) and it ran great until the last couple of miles when it started trying to stall. Subsequent troubleshooting leads me to believe poor charging and a ran down battery was the problem. I initially thought the halogen headlight bulb and incandescent taillight bulb were the main culprits as with the lights off the battery voltage would go to over 14 volts at 3K to 4K rpm but following advice from @stl360+450 to do a AC check of the stator I believe I have a bad unit. Also thanks to @stl360+450 for the link to @66Sprint's lecture on this subject, good stuff!
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When you say the bike started to stall was it trying to stalling while you were riding down the road or was it when you were stopped and it was dying during idle? I ask because I was just out riding my bike and it was running well down the road but trying to stall when stopped. Wondering if I am experiencing the same thing as you!
 
In my case we were riding doing about 45-50 MPH and probably 3-4K RPM and I felt it stall, start. stall and we pulled over pretty quickly. In the parking lot the bike would crank run and then stall again. Got it going and about a mile or so down the rode finally thought to turn off headlight. Ran OK another mile or so home. I am not 100% certain this is what my issue is but this is what I am running with. Changing to LED lights to reduce the load and hopefully I will have info to report this weekend.

How old is your battery? What was it's state of charge after you got home? Battery is always where I look first and go from there especially after working 10 years part time at an auto parts store and seeing all the weird crap a bad or almost bad battery can cause. Poor connections and grounds come in a close 2nd and are usually cheaper to fix.
 
RobMan said:
In my case we were riding doing about 45-50 MPH and probably 3-4K RPM and I felt it stall, start. stall and we pulled over pretty quickly. In the parking lot the bike would crank run and then stall again. Got it going and about a mile or so down the rode finally thought to turn off headlight. Ran OK another mile or so home. I am not 100% certain this is what my issue is but this is what I am running with. Changing to LED lights to reduce the load and hopefully I will have info to report this weekend.

How old is your battery? What was it's state of charge after you got home? Battery is always where I look first and go from there especially after working 10 years part time at an auto parts store and seeing all the weird crap a bad or almost bad battery can cause. Poor connections and grounds come in a close 2nd and are usually cheaper to fix.
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Seems like my situation is slightly different but like you said it could still be battery related. My battery an AGM type and is probably 1.5 years old and I keep a battery tender on it over the winter. It's very possible I ran it down a bit this spring as I was working on some ignition issues. I am going to measure the battery tomorrow to see if it's low on juice. I know grounding issues all too well!!
 
lundy341 said:
Seems like my situation is slightly different but like you said it could still be battery related. My battery an AGM type and is probably 1.5 years old and I keep a battery tender on it over the winter. It's very possible I ran it down a bit this spring as I was working on some ignition issues. I am going to measure the battery tomorrow to see if it's low on juice. I know grounding issues all too well!!
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Definitely look at the battery first, may just be low and the charging system couldn't keep up at idle.
 
Are you saying it doesn't charge with the 22W LED headlamp on? My LED headlamp is 30W, and the battery charges just fine; I also have a high-brightness LED from Diode Dynamics in the tail lamp, which saves a few Watts, too.
 
WintrSol said:
Are you saying it doesn't charge with the 22W LED headlamp on? My LED headlamp is 30W, and the battery charges just fine; I also have a high-brightness LED from Diode Dynamics in the tail lamp, which saves a few Watts, too.
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No I just got the LEDs and have not had a chance to test ride it and see how it does. Sorry for not making that more clear.
 
That will change things, then. I have one of those LED battery monitors, and sometimes, if I have to idle too long, I switch the headlamp off so it pops back up. When rolling, it never drops out of green with the lights on.
My main problem with LED bulbs is finding one that spreads the light properly through the lens. Once found, though, that 30W is SO much brighter than the stock candle.
 
The one I got from Amazon is advertised at a paltry 400% brighter, which is probably overkill as I probably will not be driving at night. I will need to readjust before taking it out so I don't blind anyone.
 
As a side note after about 180 miles I did pull the oil filter cover and clean the cup and and only noted a very small amount of grey sludge and only a few sparkles when wiping up with a clean rag. Also none of it appeared to be magnetic that I could see. :)
 
Fresh oil and ready for a test ride. Battery voltage at 12.85 so decided to do a run to see if battery would charge, hold steady or drop. Nice weather if a little hot, around 88 F when I took off. Did a 18 mile run keeping the engine around 4k for most it. Had headlight turned on for most of the ride and bike ran great. After I got home I did a voltage and it dropped, 12.6! What the heck, oh yeah and as the Great Gazoo would have told Fred Flintstone, Hey DumDum it works better if you connect the cable from the alternator to the main harness. No neutral light should have been the clue! Anyway connected the confirmed and confirmed that it showed it was charging but to hot for another test ride. Great excuse for another ride tomorrow!
 
RobMan said:
No neutral light should have been the clue! Anyway connected the confirmed and confirmed that it showed it was charging but to hot for another test ride. Great excuse for another ride tomorrow!
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I'm impressed that you did the whole ride without the neutral light — I've had my bulb burn out once or twice and I definitely prefer having it to not having it!

I like the Great Gazoo imagery! Enjoy that next [test] ride!!
 
400% seems to be based on the average equivalent Wattage; the average conversion from LED Wattage to incandescent Wattage is 4-6 times, so 22W is equivalent to about 88-132W. Of course, the increase in Wattage is not linear with increase in brightness, but it is a fair comparison, provided the lens efficiency is the same. I had a xenon bulb in mine for a while and, while very bright, the light spread made it less efficient. The LED I installed is a much better match to the lens geometry, making for much improved vision down the road.
 
I actually got it from a listing on eBay eleven years ago; no brand name, just a description: "5th Gen H4 LED bulb copper braid 3000 lumen CREE 6000K". I just got lucky that it matched the lens so well. Others did not.
 
Follow up test ride with the alternator PROPERLY connected and charging the battery for about an hour or so and and voltage was at 12.8 bolts and after an 18 mile run with headlight on the battery was reading 13.7 volts. I believe I can call the charging issue resolved but will continue to monitor and may get a handlebar mount voltmeter just to keep and eye on it..
 
Curious, what’s the minimum amount of voltage for these bikes to run properly? What voltage would you want the battery to be charging to if the charging system is functioning properly?
 
lundy341 said:
Curious, what’s the minimum amount of voltage for these bikes to run properly?
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If the battery won't hold at least 12.6v at rest it won't run these engines for long unless you start the bike and immediately get on the road (with a good charging system) so the rpms stay above 2500 to 3000 where the charging system starts to break even. These older charging systems actually discharge at idle so idling with the headlight on for a while will take them down.
lundy341 said:
What voltage would you want the battery to be charging to if the charging system is functioning properly?
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With a good charging system equipped with a modern rec/reg unit, the battery should top out at or below 14.5v to be safe for any aftermarket electronic ignition you might install. It won't get there right away if you warm the 450 up as it should be, a couple of minutes below the charging threshold will drag it down a bit but a good battery should bounce back pretty quickly and before you've gone far it should be well over 13v even with the headlight on.
 
Update, installed a digital volt meter/USB charging port unit on the bike. Used an extra handlebar ignition switch bracket I had in my box of spare stuff. I had to enlarge the opening some using a 1/2 round ******* file to make it fit. Couldn't take pictures of the display due to the refresh rate but started out battery at 12.8 V, then 11.2 V with starter engaged and then 12. 5 V after it started running. Let it warm up several minutes and voltage came up to 12.7 V. Ran the engine up to 3.5 to 4 K RPM and voltage appeared to max out at 13.8 V and after shutting off settled at 13.2 V. A longer run will tell more of a story and how it does at speed with the lights on.


IMG_5455.jpg
 
What battery do you run ? lead acid ? reading you post, that you ride the bike around 4K rpm, I would say that you have to be careful not to overcharge the battery when riding the bike with 6K+ rpm. Keep an eye on the voltmeter, everything above 14,8 for a longer period, is too much.

On my 450, I keep my rpm between 5,5K en 8K, sometimes a little higher, but I need to re-fill my battery every half year (Acid-lead). I did read somewhere you used to ride a Harley.....

The lubrication is good above 4K, I would spend the most time above that number.
 
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jensen said:
What battery do you run ? lead acid ? reading you post, that you ride the bike around 4K rpm, I would say that you have to be careful not to overcharge the battery when riding the bike with 6K+ rpm. Keep an eye on the voltmeter, everything above 14,8 for a longer period, is too much.

On my 450, I keep my rpm between 5,5K en 8K, sometimes a little higher, but I need to re-fill my battery every half year (Acid-lead). I did read somewhere you used to ride a Harley.....

The lubrication is good above 4K, I would spend the most time above that number.
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AGM battery with a Sparck Moto rectifier/regulator so hopefully no over charging issues. I Also have done the wire mod in the headlight bucket but I think the charging system is a little weak. When I have a chance I will take it out for a longer run and see what the meter tells me.
 
RobMan said:
AGM battery with a Sparck Moto rectifier/regulator so hopefully no over charging issues. I Also have done the wire mod in the headlight bucket but I think the charging system is a little weak. When I have a chance I will take it out for a longer run and see what the meter tells me.
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Max output is around 6-7k rpm, and since I ride my bike for longer trips only, overcharging is an issue, especially when riding highway for a longer period. A general voltage regulator will dissipate the extra power, and produce heat, lot's of it. Make sure you really need the pink/yellow connection for normal use, I don't know if you ride your bike at night.

Looking at the measured value's in your OP, the system isn't weak at all. 40+ V at 4K open contacts is a good value. The real question is what the current to the battery is @2K, 4K and 6K rpm, with and without lights on.

Do you have the possibility to measure the (DC) current to the battery from the voltage regulator ?
 
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I have had my CB450 K5 about 7 months now. The previous owner installed the Rectifier/Regulator from the guys in Houston, also did the bypass so that both windings are used for charging. It hasn't given me any problems at all. I run the headlight when riding all the time. It has the yellow MotoBatt that is approximately 1 year old. If I connect the maintainer charger that came with it, it only charges a few minutes and is topped off. Never measured any voltages because it is working fine.
 
In the US it is expected, and maybe required, to have your headlamp on day or night, although I do turn it off if I think I'll be at a stop light for more than a minute or so. I have the yellow-white wires connected in the headlamp, but, even with the lights off, the Voltage still slowly drops unless I raise the rpm by a few hundred. I have a linear type regulator (not the normal shunt type) feeding an AGM battery; overcharging is not an issue. Also, all bulbs but two turn signals are LEDs, but the system still doesn't quite keep up at idle, lights on or off.

I'll be replacing the harness soon, so maybe wires that aren't 56+ years old will improve things, but I doubt it.
 
Only my taillight is LED, the rest are bulbs, including the headlight. In the Netherlands, you use the daylight riding lights, as well as as the taillight, and when pink and yellow are combined, with lights out, the battery is overcharged. I guess my rotor is in good shape then.
 
Greybeard70 said:
I have had my CB450 K5 about 7 months now.
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7 months, how many miles did you add to the bike in those 7 months ? and how many miles high-way use are part of that ?

In 7 months, I do 3000-5000 miles, 50 to 70 % highway, rpm, is always above 5K, and mostly around 7K on highway use. Maybe your setup is fine, for your style, but that doesn't mean it's fine for everybody. I never used a trickle charger, I use the bike too much, no need for that.
 
The stock regulator only stops one half the charge current from the stator, so it is certainly possible it will let the battery overcharge, especially at the rpm you typically ride. My linear regulator reduces or blocks all power from the stator, as needed, when the battery reaches full charge. It does have a large heat sink.
 
jensen said:
7 months, how many miles did you add to the bike in those 7 months ? and how many miles high-way use are part of that ?

In 7 months, I do 3000-5000 miles, 50 to 70 % highway, rpm, is always above 5K, and mostly around 7K on highway use. Maybe your setup is fine, for your style, but that doesn't mean it's fine for everybody. I never used a trickle charger, I use the bike too much, no need for that.
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I have put about 1000 miles riding around town. I have my Harley for highway riding. It takes me back to being a teenager, I had a 1972 CL450 in 1973 for three weeks before I totaled it when a truck turned in front of me coming the other direction. This is the 3rd 450 I have owned, fell in love with the style before I was old enough to ride. My current 450 has 32,000 miles and doesn't appear to have ever been rebuilt, just well maintained. I ride just for pleasure and have owned a motorcycle since I was 15, I turn 70 in May.
 
jensen said:
Do you have the possibility to measure the (DC) current to the battery from the voltage regulator ?
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I do an automotive tester that reads up to 15 amp DC but I plan on holding off on that until I have a chance to take the bike for a long ride and monitor the volt meter as I ride. As long as the alternator can keep up while I am riding then it is good to go for now.
 
Been busy with chores for the last few days but found some time for a short ride yesterday. Battery started out about 12.8 volts and with lights on and my phone hooked up to the voltmeter USB outlet. After about 10 miles voltage got up to 13.8 to 13.9 at an average of 4K RPM and when I got on it a bit up to to 7-8 K when accelerating after turning around to head home it topped 14 volts but then settled back to 13.9. I am going to call the charging system good as long as I am using LED headlight and taillight.
 
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