Topic: 74 cb750 battery dies while riding

[United.Cycles]

Having issues with the charging system. CB750- battery dies and bike shuts off while riding. Using ricks reg/rec with antigravity lithium ion battery. Not sure where to start. Is it a rec/rec issue or the stator? It should be wired up correctly. How do I go about chasing this issue and testing these components? I have the bike charging up now.


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[bryanj]

Most likely the battery and regulator as both those dont like vibration.
Never seen a field or stator fail unless physically damaged in an accident.
Also possible that connections are bad.

There have been many posts on this subject saying where to do voltage checks, long distance electrical diagnosis is just about impossible

[United.Cycles]

Most likely the battery and regulator as both those dont like vibration.
Never seen a field or stator fail unless physically damaged in an accident.
Also possible that connections are bad.

There have been many posts on this subject saying where to do voltage checks, long distance electrical diagnosis is just about impossible

Tested the stator - got a reading of about .5 OHMS for each yellow wire. Then tested the battery at both idle and reving to higher rpms and the voltage stays around 12.7-12.9 , no change. Someone said that is a stator problem, others saying reg/rec. So I’m lost. Any idea with those readings?


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[scottly]

Having issues with the charging system. CB750- battery dies and bike shuts off while riding. Using ricks reg/rec with antigravity lithium ion battery. Not sure where to start. Is it a rec/rec issue or the stator? It should be wired up correctly. How do I go about chasing this issue and testing these components? I have the bike charging up now.


Sent from my iPhone using Tapatalk

One of the quick-and-dirty tests on a 750 is to check the screws for the field coil to see if they are magnetized with the key on and engine not running. If they are not magnetized, it means there is a problem on the regulator/field coil side of the charging system. If they are magnetized, it points towards an issue on the stator/rectifier side.

[United.Cycles]

Having issues with the charging system. CB750- battery dies and bike shuts off while riding. Using ricks reg/rec with antigravity lithium ion battery. Not sure where to start. Is it a rec/rec issue or the stator? It should be wired up correctly. How do I go about chasing this issue and testing these components? I have the bike charging up now.


Sent from my iPhone using Tapatalk

What voltage do you measure at the battery terminals withe the engine running at 2000, then 3000RPM?
One of the quick-and-dirty tests on a 750 is to check the screws for the field coil to see if they are magnetized with the key on and engine not running. If they are not magnetized, it means there is a problem on the regulator/field coil side of the charging system. If they are magnetized, it points towards an issue on the stator/rectifier side.

Just replied to the comment above with my readings of that helps, both from stator and battery while running. I saw little to no change at all at idle and reving to 3000rpm, both staying around 12.5-12.7V


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[scottly]

Check to see if the field is magnetized. 

[bryanj]

Like i said, never seen a bad stator unless physicaly damaged and i have been working on these since mid 70's.
Reg/rec and or bad connections.

There are pages of electrical tests in the Honda manual and they need to all be done in order to have any hope of proper diagnosid

[scottly]

long distance electrical diagnosis is just about impossible

Only impossible for those without proper training...

[calj737]

long distance electrical diagnosis is just about impossible

Only impossible for those without proper training...

or that lack the attitude to try to help…

[bryanj]

I have tried with several members and every last one has gone off on a tangent instead of doing and reporting tests asked for and unless testing is done methodicaly you will not find the problem.

[beemerbum]

I never cease to be amazed by how well the old systems work in old bikes. My K1 as well as my K2 750's have totally original rectifier, regulator systems. Both bikes have over 50K miles and charge their batteries without fail so far.

[United.Cycles]

The yellow wires from stator are reading .5 OHMS from each wire. When running, the bike is reading 12.9V at idle and 13.1V at 5k RPMs. From my understanding at higher RPMS the Voltage reading should be in the 14s. I’ll try the magnetic test. I have to swap the bolts out since they were changed to stainless steel.


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[calj737]

The yellow wires from stator are reading .5 OHMS from each wire. When running, the bike is reading 12.9V at idle and 13.1V at 5k RPMs. From my understanding at higher RPMS the Voltage reading should be in the 14s. I’ll try the magnetic test. I have to swap the bolts out since they were changed to stainless steel.

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Fire up the bike, stick a lightweight wrench to the stator cover. Does it hold? No need to swap bolts around.

[United.Cycles]

The yellow wires from stator are reading .5 OHMS from each wire. When running, the bike is reading 12.9V at idle and 13.1V at 5k RPMs. From my understanding at higher RPMS the Voltage reading should be in the 14s. I’ll try the magnetic test. I have to swap the bolts out since they were changed to stainless steel.

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Fire up the bike, stick a lightweight wrench to the stator cover. Does it hold? No need to swap bolts around.

I’ll give it a try. If the wrench doesn’t hold, bad stator?


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[scottly]

One of the quick-and-dirty tests on a 750 is to check the screws for the field coil to see if they are magnetized with the key on and engine not running. If they are not magnetized, it means there is a problem on the regulator/field coil side of the charging system. If they are magnetized, it points towards an issue on the stator/rectifier side.

[HondaMan]

I never cease to be amazed by how well the old systems work in old bikes. My K1 as well as my K2 750's have totally original rectifier, regulator systems. Both bikes have over 50K miles and charge their batteries without fail so far.

Mine, too, at 3x that mileage!

[Deltarider]

I never cease to be amazed by how well the old systems work in old bikes. My K1 as well as my K2 750's have totally original rectifier, regulator systems. Both bikes have over 50K miles and charge their batteries without fail so far.

Mine, too, at 3x that mileage!

My 48 yr old CB500 has done 90k miles now and all electrics are still the original parts. Apart from the fuse clips, I have had no indication for even cleaning the connectors. The Yuasa battery is now 7 years and 3 months old. All starts have been electric. A new battery purchased 15 months back, is - still dry - waiting on the shelf.

[Deltarider]

Had to replace the key IGN switch, due to my 'maintenance'. I had sprayed the interior with WD-40 which had turned some of the plastic into goo that prevented good contacting.

[HondaMan]

A new battery purchased 15 months back, is - still dry - waiting on the shelf.

That's a good plan! It takes a long time to get new AGM batteries right now.

[scottly]

I never cease to be amazed by how well the old systems work in old bikes. My K1 as well as my K2 750's have totally original rectifier, regulator systems. Both bikes have over 50K miles and charge their batteries without fail so far.

Mine, too, at 3x that mileage!

My 48 yr old CB500 has done 90k miles now and all electrics are still the original parts. Apart from the fuse clips, I have had no indication for even cleaning the connectors. The Yuasa battery is now 7 years and 3 months old. All starts have been electric. A new battery purchased 15 months back, is - still dry - waiting on the shelf.

While I understand the love you guys feel for all stock parts, none of this helps the OP fix his charging system.

[bryanj]

Trouble is Scotty it is quite probable the non stock parts are the problem

[calj737]

Trouble is Scotty it is quite probable the non stock parts are the problem

Most likely culprit is incorrect wiring of the new parts, not faulty new parts.