Topic: CB750K4 - new updates 11 Oct 2024 bike not charging - need help!

[scottly]

Andy, does the electric starter work OK?

[andy750]

Andy, does the electric starter work OK?

Yes it works fine no issues.

[MRieck]

99% of the modern alternator charging failures saw at my shop where cause by a bad stator. Did quite a few Kawasaki Vulcans.

[newday777]

Andy
Just a thought, have you put a multimeter on to verify the on board voltmeter recently? Is the voltmeter digital?
I have a digital voltmeter on my wing that has been reading low. They do go bad.

[MRieck]

Are you running the R6 charging system or just a modern reg/rec Andy. I thought you had the whole system but that me be in the other 750??

[newday777]

Are you running the R6 charging system or just a modern reg/rec Andy. I thought you had the whole system but that me be in the other 750??

Andy said it was Anders whole system yesterday.

[andy750]

Andy
Just a thought, have you put a multimeter on to verify the on board voltmeter recently? Is the voltmeter digital?
I have a digital voltmeter on my wing that has been reading low. They do go bad.

I did thanks and I have two to compare as well. Def no charging

[andy750]

Are you running the R6 charging system or just a modern reg/rec Andy. I thought you had the whole system but that me be in the other 750??

Thanks Mike for the great question 😎 whatever Anders put in is what I have. He did the alternator upgrade with charging system. How do I tell it’s an R6 charging system?

[MRieck]

Are you running the R6 charging system or just a modern reg/rec Andy. I thought you had the whole system but that me be in the other 750??

Thanks Mike for the great question 😎 whatever Anders put in is what I have. He did the alternator upgrade with charging system. How do I tell it’s an R6 charging system?

I've gone over that unit many times with Anders....a lot of his decision to use those parts was availability. the R6 remained basically the same for like 10 or 12 years. Lots of used parts in comparison to other modern bikes. I run it in my bike and it is great. I have 2 new units on hand ...text me when is a good time to call and we'll talk. Like I said early....it is generally the stators that give out. In general the reg/rec will only do with what it gets for charge. I'm not saying the reg/rec is impervious to failure it is just fairly rare in my experience. Always a good idea to run a separate ground wire from the reg/rec to a good ground point.

[scottly]

Mike, is the R6 stator 3 phase, like the Honda stator? I would start by checking the resistance between the stator wires. Also, the reg for a permanent magnet system is a "shunt" regulator, that burns off excess power to ground to limit the max voltage.

[MRieck]

Mike, is the R6 stator 3 phase, like the Honda stator? I would start by checking the resistance between the stator wires. Also, the reg for a permanent magnet system is a "shunt" regulator, that burns off excess power to ground to limit the max voltage.

As far as I know it is.....aren't most of them brother? I'm not the brightest electrical fella that's for sure....you have a lot over me when it comes that. And you are correct about the shunt function. I've had more problems with bikes that use automotive type alternators like FJ11/1200's etc....they generally overcharge and you really can't do much to stop it.
 

[scottly]

3 phase will have 3 wires, while single phase only has 2 wires. Most alternators are 3 phase, but it's best not to assume. If the stator is at fault, checking the resistance should show it. It should be the same between each of the 3 wires: A to B, A to C, and B to C, and is generally a very low resistance, such as .2 ohms, but don't expect a typical meter to read that low value accurately. Also, there should be no continuity from the wires to the engine case, at least with a Honda stator. 

[scottly]

Looking at the first pic, it looks like 3 pink wires with black bands are in the forward plug on the bottom of the rec/rect. Do those wires go under the shifter cover? If so, they are probably the stator wires. With the plug disconnected from the reg/rect, measure the resistance between the leads. Set the meter on the lowest ohms scale, touch the leads together, and note the reading, then measure the stator leads.

[MRieck]

It was 3 phase....3, white wires .

[PeWe]

Verify all connections. Might be a bad crimp or connector not locked.

I have found crimped wires with insulation not removed where crimped. Mistake by operator/machine when crimping in a machine that remove insulation and crimp within a sec.
It worked for a year, strands sticking out with contact later corroded. Lover voltage/current, D-sub connector.

Not on a CB, at my job, industrial equipments.

[MRieck]

Here's a video Andy that easy to follow. 

[andy750]

Thanks Mike super helpful! Will text you after this post and hopefully we can chat.

Thanks Scottly and Per for the input and easy to follow instructions! If I have time tomorrow (day off work) Ill take stator cover off and check connections - on my K2 this was the issue - corroded wires to the stator.

If not tomorrow then may be delayed but will update when I find out more.
thanks
Andy

[scottly]

Andy, before you remove the alternator cover, try measuring the stator wires at the plug on the reg/rect.

[andy750]

Ah yes would be easier for sure. Ok I’ll do this tomorrow morning for sure and report back. Thank you!

[andy750]

CB750 issues must be contagious

http://forums.sohc4.net/index.php/topic,32093.new.html#new

Ok update as promised....

First off had a hard time getting the plugs separated and had to remove the airbox as the lower airbox wingnuts were stuck  ...anywya made it easier to get to the wiring.

See photos - a white connector with two wires comes out of the alternator along with the 3 white wires going to the Regulator Rectifier (reg/rec). I removed the gray plug from the reg/rec and measured the Ohms from A-b, b-c, a-c, all read 107.4....is this good?

Did not run the bike and test alternator.

What should I do next?

Based on reg/rec markings looks like its this one:
https://www.amazon.com/Voltage-Regulator-Rectifier-FH012AA-1D7-81960-00-00/dp/B07LC1GMT5

Thanks
Andy

[Alan F.]

Do any of your A-B-C have continuity to the "alternator" cover?

[scottly]

I removed the gray plug from the reg/rec and measured the Ohms from A-b, b-c, a-c, all read 107.4....is this good?

No, that's very bad. I found a spec quoted for the r6 stator as 0.18-0.26 ohms, and another as 0.27-0.33 ohms; evidently there was some variance over the years. Just to rule out any measurement error, what does your meter read when you touch the two meter leads together?

[andy750]

I removed the gray plug from the reg/rec and measured the Ohms from A-b, b-c, a-c, all read 107.4....is this good?

No, that's very bad. I found a spec quoted for the r6 stator as 0.18-0.26 ohms, and another as 0.27-0.33 ohms; evidently there was some variance over the years. Just to rule out any measurement error, what does your meter read when you touch the two meter leads together?

Looks like the issue is me - when I put the two leads together it reads 156 on the 200 Ohm scale

[scottly]

Looks like the issue is me - when I put the two leads together it reads 156 on the 200 Ohm scale

No, looks like the issue is your meter. Try replacing the battery.

[andy750]

Ok replaced battery with a Duracell 9v I had in my battery box (age unknown) and reading is now 88. What should it be? Zero? 😎