Q about rotors and the alternator.

[MEHall]

Is there any rotors that dont need brushes for the CB 650 motor? I also have trouble to losen the screws and bolts in the alternator cover. So that means i cant replace the brushes.
What should i do to get them loose?

[tidd650]

You may want to start with some penetrating oil. I had to use an impact wrench, as I had a heck of a time getting mine loose.

[MEHall]

Oh, my bad. I should have said that i tried that but to no avail.
I only have been able to change one of the screws on the brush base from Phillips to Allen type. But the other screw got damaged in the process of trying to remove it. So it's Phillips head is damaged so no Phillips screwdriver wont work any more.
I got another alternator cover so i only need to get the brush base and the alternator coils loose from the old cover.

[Volker_P]

Welcome here!

As the air gap is very small and coils probably won't just come out easily, I doubt a bit that one can just swap the stator coils from one cover to another without running into trouble. So keep that as your very final option.

I don't now how it looks like there at the moment, maybe you can cut a slot with a saw and use a normal screwdriver together with pliers on the outer rim of the bolt head. Often a good, central hit with a hammer helps to loosen steel bolts in alumina. But make sure you don't bend anything that way.
If all this should not work and you can show a picture, I might get another idea.

The brushes are needed to supply 12V DC to the rotor. It might work in principle with a permanent magnet rotor, too. However you will have to make this one yourself and get a new idea about voltage regulation. And power will be lower, probably insufficient for much more but ignition.

BTW, what's your problem? The typical charging issue of a CB650 seems to be rotor failure.

[MEHall]

I know as i have changed both the rotor and the regulator/rectifier.
I have noticed that the brush that is going on the outer contact surface is softer in the spring. I have bought brushes but cant change it because that faulty screw that holds the brush base. I really wonder if a brush that is softer in the spring can cause lesser charge?
I must say it's nearly impossible to get an hacksaw blade in place where that busted screw is though.
I could use my dremel like tool and mill the screw head off though.

[Volker_P]

I'd assume a weaker spring may reduce contact quality resulting in sparks and wear. This would probably imply that the corresponding brush is already shorter and the slipring is darker or even has already a rough surface.
At least that is what I observed some time ago at a starter motor due to a sticky brush. Which is however still a bit different kind of problem.

As the rotor circuit seems to be tuned by the regulator, a limited additional contact resistance (no excessive wear and everything looks smooth and clean) should be no problem. You may try to measure rotor resistance directly at the sliprings and again when installed at the brushes.

Changing parts is one thing, better measure the rotor/stator resistance.
Stator should be 0.4 - 0.5Ohms between all three yellow cables, no ground contact. Rotor resistance should be in the order of 4-10Ohms.
Be aware that measuring small resistances with a cheap multimeter might imply errors. The only thing they measure quite good is typically voltage.

[cb650]

Did you try a impact driver? Best thing for stuck phillips head.

[MEHall]

Volker_P. i have checked and checked again and all looks fine with the resistance, and the new rotor i have installed should be ok tho.
cb650, the head on the old Phillips screw is so busted so no Phillips screwdriver can engage in it so i rather mill it off.
My Suspicion is the brush that there is lesser spring on.
I did fix it so it worked temporary with correct charge but when the bike had traveled a quite distance it wouldnt charge correct.
So what i relly have to do is getting that faulty screw off and change both brushes so i can be sure it works correctly.