Topic: ‘81 Honda cb650C: Bad rotor/stator?

[Cruiser87]

Hi! Does this rotor look bad to y’all? It has some visibile cracking on the surface there.
; Is it typical for the rotor to have that glazed appearance like that?

And does this stator look normal? I haven’t seen any others with that wierd glaze on em like that when searching stators
I’ve been having charging system issues so I’m going over it all, I just received a new rr in the mail today to replace my last faulty one, but thinking I need a new stator, and possibly a new rotor if this one is dunzo..also my connections looked like this when I first took em off..TOTAL CORROSION

 any insights/help would be greatly appreciated!!!

Thanks for havin me! Oregon first time rider figurin his first bike out tryna get it purrin nice before the summer is over!!! Cheers !!!

-cal

[onepieceatatime]

Clean the corrosion from those connections then apply silicone grease to help keep moisture out.
I would clean the sliprings on the rotor too.
The rotor is the most common failure point on these charging systems.
Measure the resistance between the sliprings on the rotor. It should be between 4 and 10 ohms. Neither slipring should be shorted to the body of the rotor.
Measure the resistance between the yellow wires of the stator. It should be between 0.4-0.5 Ohms, symmetrical between each pair of yellow wires. None of the wires should be shorted to the stator mounts.
If your measurements meet these criteria, then your parts should be ok.

[bryanj]

Thats not wierd its standard varnish insulation

[Cruiser87]

Clean the corrosion from those connections then apply silicone grease to help keep moisture out.
I would clean the sliprings on the rotor too.
The rotor is the most common failure point on these charging systems.
Measure the resistance between the sliprings on the rotor. It should be between 4 and 10 ohms. Neither slipring should be shorted to the body of the rotor.
Measure the resistance between the yellow wires of the stator. It should be between 0.4-0.5 Ohms, symmetrical between each pair of yellow wires. None of the wires should be shorted to the stator mounts.
If your measurements meet these criteria, then your parts should be ok.

Thanks so much for the tips mate!

So I cleaned the slip rings with some 600 grit and kept getting a reading of 2.8 resistance.
The rings were Not grounded to the rotor body.

And for the stator check, I cleaned the corrosion off with some vinegar and the 600 grit.
The yellow wires tested against each other all gave a reading of .6 .
And the stator passed the ground test as well. (This is the same as testing for continuity I’m assuming?)


Sounds like possibly bad rotor as well as a bad stator?

[onepieceatatime]

Clean the corrosion from those connections then apply silicone grease to help keep moisture out.
I would clean the sliprings on the rotor too.
The rotor is the most common failure point on these charging systems.
Measure the resistance between the sliprings on the rotor. It should be between 4 and 10 ohms. Neither slipring should be shorted to the body of the rotor.
Measure the resistance between the yellow wires of the stator. It should be between 0.4-0.5 Ohms, symmetrical between each pair of yellow wires. None of the wires should be shorted to the stator mounts.
If your measurements meet these criteria, then your parts should be ok.

Thanks so much for the tips mate!

So I cleaned the slip rings with some 600 grit and kept getting a reading of 2.8 resistance.
The rings were Not grounded to the rotor body.

And for the stator check, I cleaned the corrosion off with some vinegar and the 600 grit.
The yellow wires tested against each other all gave a reading of .6 .
And the stator passed the ground test as well. (This is the same as testing for continuity I’m assuming?)


Sounds like possibly bad rotor as well as a bad stator?

What does the meter read with the leads just touching each other? You have to subtract that from your readings to get a correct measurement number. I am willing to bet that the stator is ok, but it sounds like your rotor will need to be rewound or replaced. There used to be guy on ebay that would rewind them, might still be around, but I haven't checked recently.

Sent from my Pixel 4 XL using Tapatalk

[Cruiser87]

Clean the corrosion from those connections then apply silicone grease to help keep moisture out.
I would clean the sliprings on the rotor too.
The rotor is the most common failure point on these charging systems.
Measure the resistance between the sliprings on the rotor. It should be between 4 and 10 ohms. Neither slipring should be shorted to the body of the rotor.
Measure the resistance between the yellow wires of the stator. It should be between 0.4-0.5 Ohms, symmetrical between each pair of yellow wires. None of the wires should be shorted to the stator mounts.
If your measurements meet these criteria, then your parts should be ok.

Ah I had no idea about having to subtract the meters own reading that is a GREAT pointer thank you.

With that knowledge then, the stator gave a .5 reading for the yellow wires to each other & the slip rings gave a reading of 2.7.

Excellent! Thanks so much for the quick responses this is a lifesaver of a resource to have access to, super psyched to grab a new rotor n get er fired up!

Since the stator is testing ok, would you recommend only buying the new rotor? Or am I possibly jeopardizing my new rotor and rr by not grabbing a Fresh stator?

[onepieceatatime]

Ah I had no idea about having to subtract the meters own reading that is a GREAT pointer thank you.

With that knowledge then, the stator gave a .5 reading for the yellow wires to each other & the slip rings gave a reading of 2.7.

Excellent! Thanks so much for the quick responses this is a lifesaver of a resource to have access to, super psyched to grab a new rotor n get er fired up!

Since the stator is testing ok, would you recommend only buying the new rotor? Or am I possibly jeopardizing my new rotor and rr by not grabbing a Fresh stator?

I would just replace the rotor and rr. Keeping the stator should not be an issue.

[RAFster122s]

One thing I saw someone do when taking readings with a multimeter was to use their fingers to pinch the wire ends to the multimeter leads. Problem is doing this introduces your body into the reading and it skews the results. Not that you have done this, just thought I would mention it.

[70CB750]

I just went through this with the CB900.  Replaced rotor and brushes.  The consensus is that Rick's is the best on the market, check them out:

https://ricksmotorsportelectrics.com/l/rotors

[70CB750]

Also you will need a puller to get the rotor off. 

The rotor is on a taper and the puller is just a metric bolt.  You take out the flange bolt and drive in a bigger bolt (it is M14 for CB900, not sure of your size) and that bolt will push it off the taper.  Impact gun makes it easy, otherwise you need to put it gear and use the rear brake.

Just heads up, it took me bit of figuring out. 


BTW, got pictures of the bike?  I wonder how different it is from the CB900C 

[onepieceatatime]

Also you will need a puller to get the rotor off. 

The rotor is on a taper and the puller is just a metric bolt.  You take out the flange bolt and drive in a bigger bolt (it is M14 for CB900, not sure of your size) and that bolt will push it off the taper.  Impact gun makes it easy, otherwise you need to put it gear and use the rear brake.

Just heads up, it took me bit of figuring out. 


BTW, got pictures of the bike?  I wonder how different it is from the CB900C 

The rear axle will work as the puller bolt.

[70CB750]

Also you will need a puller to get the rotor off. 

The rotor is on a taper and the puller is just a metric bolt.  You take out the flange bolt and drive in a bigger bolt (it is M14 for CB900, not sure of your size) and that bolt will push it off the taper.  Impact gun makes it easy, otherwise you need to put it gear and use the rear brake.

Just heads up, it took me bit of figuring out. 


BTW, got pictures of the bike?  I wonder how different it is from the CB900C 

The rear axle will work as the puller bolt.

Good to know 

I built my sidecar brackets and struts on metric threads - I was lucky enough to have unused piece of M14 in my stash.