Stationary rotor assembly

[tommytwohands]

Well I’m guessing the oil seal behind this assembly was bust. The oil is dry so it must have been fixed by the PO who didn’t bother to clean the pieces.

WB-40 or degreaser be acceptable to use to clean? I may have a short to ground anyway on the rotor and stator, but a second multimeter will soon confirm this. So I may be in the classified section soon enough looking for some parts.
Is a shorted rotor as good as dead or can it be rewound and saved?

 

[GLJ]

Is a shorted rotor as good as dead or can it be rewound and saved?

@Jim can fix up up with a rewound as good or better than new rotor if needed.

 

[5twins]

The stator (your 2nd pic) is the stationary part. The rotor is the part that spins inside it, located behind and inside it. You'll have to remove the stator to get at the rotor (simple, just 2 screws), and it's best to use the correct puller to remove the rotor.

 

[tommytwohands]

The stator (your 2nd pic) is the stationary part. The rotor is the part that spins inside it, located behind and inside it. You'll have to remove the stator to get at the rotor (simple, just 2 screws), and it's best to use the correct puller to remove the rotor.

View attachment 212165

Oh yeah, I worded that oddly. I checked through the stator window at the outer slip ring of the rotor and the center bolt and I have a resistance so I took as a short to ground indication. I guess I haven’t done any stator tests yet so I jumped the gun. Maybe a deep clean of both will help

 

[5twins]

Yes, if the slip rings on the rotor are very dirty (with carbon rubbed off the brushes), that can cause connection issues. The simple rotor test is to measure between the two slip rings. You want to find 4 or 5 ohms resistance. It's easiest to do the measuring with the stator removed. You have to at least remove the brushes. I don't know what all that "goop" is all over your brush block (silicone caulk maybe?), but it's not supposed to be there. The block and all it's parts (screws, wires) should be clean .....

 

[Jim]

I checked through the stator window at the outer slip ring of the rotor and the center bolt and I have a resistance....

Were the brushes Disconnected?

 

[tommytwohands]

It’s silicone. I’ve been scrapping it off.

Nah Jim, I removed them to check for adequate length. I still need to do that. I wanted to remove the stator today but don’t have a #3 Phillips and Easter hours mean all hardware stores near me are closed.
Tried a #2 and began the process of stripping the screws

 

[Jim]

These are JIS screws, not phillips. You need JIS screwdrivers.

 

[tommytwohands]

Yes, if the slip rings on the rotor are very dirty (with carbon rubbed off the brushes), that can cause connection issues. The simple rotor test is to measure between the two slip rings. You want to find 4 or 5 ohms resistance. It's easiest to do the measuring with the stator removed. You have to at least remove the brushes. I don't know what all that "goop" is all over your brush block (silicone caulk maybe?), but it's not supposed to be there. The block and all it's parts (screws, wires) should be clean .....

View attachment 212166

I’ve read conflicting information on cleaning the stator and rotor. Have you any input? Some seem to say not to touch the pieces and some no, you can clean without worry with degreaser or mineral spirits. You’ve consistently helped me, 5Twins, so I figured if you had any input I’d take that into consideration.

These are JIS screws, not phillips. You need JIS screwdrivers.

That would explain why I'm moving on to drilling off the head of the screws as we speak. Thanks a bunch Jim, will keep that in mind and pick one up

 

[650Skull]

It’s silicone. I’ve been scrapping it off.

Nah Jim, I removed them to check for adequate length. I still need to do that. I wanted to remove the stator today but don’t have a #3 Phillips and Easter hours mean all hardware stores near me are closed.
Tried a #2 and began the process of stripping the screws

Dont need JIS standard screwdrivers in these screws..................If you look they all have the choice of using a spade screwdriver or the X, (jis), head screwdrivers

 

[Jim]

That would explain why I'm moving on to drilling off the head of the screws as we speak. Thanks a bunch Jim, will keep that in mind and pick one up

In a pinch, you can grind down a phillips bit like this.
I say in a pinch.... that's all I use anymore. I think it works just as good.

 

[Jan_P]

Try to make a slot with a hacksaw blade if nothing else works and then use a flat screwdriver or impact wrench

If the copper winding is dirty it can still be possible to save perhaps
Not exactly sure here but in transformer windings the wire is covered with something ( Lacquer ? )
that prevents conduction between the windings if using the wrong cleaning solvent that cover is washed off and needing a $ 100 rewind

Here are firms that rewinds motors for industry and farming I would consult them.
I don't think dirt itself is dangerous so much

 

[Jim]

Been rewinding rotors for over 3 yrs now. In all that time I haven't found anything short of sandblasting that will touch the epoxy on 'em. I've even tried paint stripper... nothing affects it. And far as I know, the stator's are wound with the same stuff. A solvent such as mineral spirits is a safe, effective way to clean 'em.

 

[Mailman]

On my ‘77D the crankshaft seal was leaking and the stator was soaked with oil. I pulled it off and set in a pan and cleaned it with kerosene, then I rinsed it off with hot soapy water followed by a clear water rinse. Then I blew it out with compressed air and set it aside to thoroughly dry out for a few days. It’s been operating perfectly ever since and that was years ago.
By the way if you decide to pull that rotor off, listen to 5Twins and get yourself a rotor puller, Mikes XS has them.
If you try and use a normal jaw puller you can ruin your rotor. Just ask Jim how many bent rotors he has to throw away!

 

[Jim]

Just ask Jim how many bent rotors he has to throw away!

I think 6, at last count.

 

[tommytwohands]

Roger that
One of the stator screws is pretty mangled. Would using a left handed drill bit be the final nail in the coffin for this screw? Or dremel off the head? Obligatory haven't done this before and

 

[Jim]

You could try the LH drill but It's probably corroded pretty good, so.... Did you try cutting a slot like Jan suggested above?
Next would be removing the head of the screw.

 

[tommytwohands]

You could try the LH drill but It's probably corroded pretty good, so.... Did you try cutting a slot like Jan suggested above?
Next would be removing the head of the screw.

Tried cutting a slot, top to bottom. Put in a flat head tight and it would not budge, just widened the slit after multiple attempts and now isn’t useful. Maybe I’ll try again side to side with a longer handle/more torque.
Guess I’ll have to try my hand at cutting off the head of a screw at some point in life

 

[Jim]

Guess I’ll have to try my hand at cutting off the head of a screw at some point in life

I don't cut, I drill the heads off.
Screw is a 6mm. Drill into it with a 6mm drill bit and the head will pop right off.

 

[tommytwohands]

I don't cut, I drill the heads off.
Screw is a 6mm. Drill into it with a 6mm drill bit and the head will pop right off.

Okay thank you for that detail. I’ll have to buy a drill officially
Early 20 year old here, first bike and my dad’s old tool boxes is what I’m working with.