Topic: 1973 CB500f is not charging

[foomcb5f]

I purchased a 1973 CB500f 2 weeks ago. I rode it for a few minutes and then the bike died. Turns out my battery was low on charge, so I purchased a new battery and bike died again. The original rectifier and regulator are still on the motorbike.

So I read that there are 3 things to look into; Stator, Battery, Regulator/Rectifier. I immediately order 2 Regulator units from Amazon.

I started testing my stator according to the service manual  (page 95) and got 1.0 Ohms resistance value. My coil was 5.5 Ohms resistance value. (manual values are 0.35 & 4.9)

I search youtube found a video (https:///youtu.be/BVXnbrigYf8) on how to check stator conditions. So I checked the continuity to ground making sure insulation are good. (set to Ohms, one probe to ground other probe to 1of 3 yellow stator wire) PASS. Next I check the resistance reading between all 3 yellow wires. I get a resistance reading of 1.0 Ohms between all 3 wires, which means there are no breaks. My understanding is my Stator and coil are good.

Moving on to the new regulators I purchased from Amazon. They both look the same from 2 different sellers. I unplugged the rectifier and attached 3Y, 1R, and 1G to the Regulator unit. Then I attach Red,Black, White from the old regulator to the new wires from the new unit (black to black, green to green, white to white) 

Start the bike, voltage @ 12.9, rev the engine nothing no gains.

So this is where I am at, frustrated, called local shops and no one wants to touch this vintage Honda. I am searching this forum for solution atm, but I am exhausted and want to ride before the Summer is over lol. Any help would be appreciated.

Questions:

1. Are there any fuses on this motorcycle?
2. can someone please post a link on how to test the R/R units?

As a token of appreciation for any help I may receive from this forum, I will make a donation to the forum admin when my bike is up running. Thank you.

[foomcb5f]

This is one of the RR unit I purchased. They both are identical.

[bryanj]

Stator and field coils rarely,if ever, fail
Regulators very occasionaly fail
Rectifiers rarely fail unless damaged

Most common problem is bad connectors

[foomcb5f]

RR Test with diode mode POSITIVE lead:

Forward bias results (negative probe to positive wire) making .5 DC per yellow wire

Reverse bias results (positive probe to positive wire) 0 DC

RR Test with diode mode NEGATIVE lead:

Forward bias results (positive probe to negative wire) making .5 DC per yellow wire

Reverse bias results (negative probe to negative wire) 0 DC

RR checks out GOOD.

[foomcb5f]

I also tested the original rectifier, the results are the same, in good working order.

However I did notice that the connectors were faulty at first on the OEM. They are dirty and should be replace or scrubbed.

I am going leaning towards cleaning all connectors. Will test the original regulator also then reconnect to see if my problems are resolved. 

[dave500]

be sure all the contacts and connectors in any and all gang plugs are clean first,chances are the original items were ok cept for corrosion at the connectors?theres only one fuse on early 500s,if it blows you lose the lot,its inside a tin tube if still original under the left hand side cover,be sure you get the correct type of regulator,these old bikes have an electromagetic field that is adjusted by the regulator,its powered by a good battery,its a separate thing from the rectifier,most late bikes have a permanent magnet field whose regulator more or less dumps excess voltage to earth and its a combimbed unit with its rectifier,the two types aint compatible!i rarely post on electrical as its hard to explain #$%* without showing you in person,what ever the #$%* you do,DO NOT reverse the battery polarity(dont get pos and neg #$%*ed up)it WILL #$%* the rectifier and possibly wiring loom!

if youve flattened the battery recharge it with a soft charger,dont try and recharge a flat battery with the bike,all tests should be done with a good charged battery.

[PeWe]

Is 500 same as the 750 in the rectifier harness, the short red/white wire to battery +?

There is a small bullet plug between battery + cable and rectier connector. That bullet plug really badly placed and can be oxidated or even loss.

[Bodi]

The field and stator coils, as Brian posted, rarely fail. Your Ohmeter test says they are OK.
Same with the original rectifier, it's proven itself sturdy. And you've checked that too.
Regulators can be trouble but are pretty reliable. The basic mechanism can't be very bad - many are still working fine after 40+ years

The biggest weakness in the whole charging system is the wiring harness. The bullet connectors are prone to corrosion and increased contact resistance after decades of exposure to the environment.
That's not a big deal for some circuits - not good but it has to get really bad before ignition fails and lamps get noticeably dim.

The charging system wiring needs good connections though. The current in the circuit is relatively high so contact resistance has an increased impact (you can't fool with Ohm's Law). All connections in the 5 alternator wires should be cleaned and checked for corrosion or failure. The bullet females should have bright metal with clear sleeves and the  males should snap in securely. If a sleeve is burnt brown - or charred black - the female may be ruined. The metal loses it's "spring" if it gets hot enough to burn the sleeve and the wire itself gets corroded for a few mm from the connector. Just a bit brown - you can try squeezing the female barrel gently with pliers to add some tension. Plug a male in and out a few times to confirm that it continues to snap in place. The block connectors to the engine and rectifier use spade connectors also prone to corrosion. Usually just unplugging and replugging these a few times is enough because the sliding contacts will cut through to good metal. If any show signs of overheating, the connector contact terminals should be replaced. They latch in the shells with little tangs and a thin screwdriver pushed in beside the wire will release them. Replacement shells and terminals are available.
Using dielectric grease on all the connections seals out oxygen and water to reduce future corrosion.

Switch contacts are another issue. They are not really serviceable though. I sit and cycle the keyswitch back and forth a few dozen times to clean the internal contacts, as preventative maintenance. If the white plastic rear part of the switch has brown spots indicating overheating ... it's probably close to failure. I have installed main power relays on a few bikes so the keyswitch only carries the relay coil power, very good idea for replacement (Emgo type) switches and not a bad move with an OEM switch. Only the keyswitch is involved in the charging circuit - pod switches are another nightmare but they won't affect charging.

[foomcb5f]

Opened the OEM regulator, looks good condition.

Although I did not like where it was mounted with the rear contacts exposed to the inside of the battery  wires.

[foomcb5f]

 Birds nest battery box setup.

Will be re-connecting with heat shrink butt connectors.

[foomcb5f]

This morning the OEM rectifier failed the NEGATIVE lead test as I remounted it back on the motorbike.

I also tested the original rectifier, the results are the same, in good working order.

However I did notice that the connectors were faulty at first on the OEM. They are dirty and should be replace or scrubbed.

I am going leaning towards cleaning all connectors. Will test the original regulator also then reconnect to see if my problems are resolved.

[foomcb5f]

we have POWER!

check all connectors, fix where needed, clean all contact points, recheck stator, regulator, rectifier, coil.

1. Bike failed to recharge because of faulty OEM rectifier (see previous bench test with multimeter)

2. New RR unit failed because of bad connectors

3. Connect new RR unit and left the OEM regulator connected --> RESULT battery charged only when rpms are up to about 15v. OEM regulator ran too hot.

4. Connected new RR unit and omit OEM regulator ---> RESULT battery charged at idle 14v, when rmps above 5000 16.5

5. Now that everything works will be fixing them connectors and wires.

Thank you .... yes I will be making a donation

 

[foomcb5f]

Buy Amazon RR at your own risk, both mine failed within 24 hours.

I am currently running one of the Amazon unit rectifier and then utilizing the OEM regulator.

[HondaMan]

Buy Amazon RR at your own risk, both mine failed within 24 hours.

I am currently running one of the Amazon unit rectifier and then utilizing the OEM regulator.

I swore off ALL Amazon [anything] 2 years ago. I bought 3 things thru them, all 3 were faulty out of the box, the vendors would not even reply to my inquiries. Never again.

Honda still sells quality parts, and vendors like PartsNmore and CB750 Supply have been good folks & parts (for me, for 12 years). 4into1 once in a while has good electrical stuff, but on the whole they only sell Chinese-made junk (like Amazon) unless it has a Japanese manufacturer on the advertised label there.

[caluser2000]

I got one of these for my CB550F. I installed it 15 months ago and no problems at all.

https://4into1.com/regulator-rectifier-lithium-lead-acid-honda-cb350f-cb400f-cb500-cb550-cb750/

Made a bracket up so it would fit under the flasher relay and remove a peice of the lower edge of the left hand side cover.

They also stock separate rectifier units to go with the standard voltage regulator.

Also check were the three yellow wires come out of the alternator winding housing for fraying/shorting. I had a CB500/4 that did have a wire short and not charging.

[foomcb5f]

Opened the OEM regulator, looks good condition.

Although I did not like where it was mounted with the rear contacts exposed to the inside of the battery  wires.

Thank You

[foomcb5f]

be sure all the contacts and connectors in any and all gang plugs are clean first,chances are the original items were ok cept for corrosion at the connectors?theres only one fuse on early 500s,if it blows you lose the lot,its inside a tin tube if still original under the left hand side cover,be sure you get the correct type of regulator,these old bikes have an electromagetic field that is adjusted by the regulator,its powered by a good battery,its a separate thing from the rectifier,most late bikes have a permanent magnet field whose regulator more or less dumps excess voltage to earth and its a combimbed unit with its rectifier,the two types aint compatible!i rarely post on electrical as its hard to explain #$%* without showing you in person,what ever the #$%* you do,DO NOT reverse the battery polarity(dont get pos and neg #$%*ed up)it WILL #$%* the rectifier and possibly wiring loom!

if youve flattened the battery recharge it with a soft charger,dont try and recharge a flat battery with the bike,all tests should be done with a good charged battery.

Thank You