CB550 K0 - Generator de-rust

[JamesH]

Well this is a first for me. Pulled the generator cover on one of my 550 K0's (suspected seized engine) and turns out it was the generator rotor / stator that had rusted and stuck together. Must have suffered from water ingress at some point and sat like this for years (US bike).

Stripped the generator down this evening and the rust is fairly significant. Anyway, had some 'metal rescue' left over from a previous project so thought I'd take the plunge and soak the parts overnight and see if it softens the rust enough for me to carefully clean up the parts. Watch this space...

[MCTID]

I spent 4 months 'salvaging' machine tools which had been submerged when the adjacent river burst its banks in Cambridge, Ontario in the 70's.

We used to strip and clean up the electric motors and then give them a really good dosing of WD40 then stick a light bulb inside the windings and wrap it all in bacofoil for a day or so.......letting the WD40 work it's magic and the heat from the bulb to dry it all out.

It generally worked out OK.

Recommended cheap fix.

[AshimotoK0]

Make sure you check for infinite resistance (open circuit)  between any of the three yellow stator wires and the mag-frame steel lamination's James, as its toast if the copper wire varnish has broken down. We have a heated bath of Bilt-Hamber deox-C at work. Pretty good at getting rid of corrosion like that. CB750 & CB250/350K stators run in oil but 500/4 and 400/4 are dry and subject to corrosion and failure (I had two 400/4 stators go bad like that  on bikes less than 10 years old).

http://www.bilthamber.com/deox-c

[UK Pete]

The rust looks quite nasty James , however as ash said as long as the windings are ok then i am sure after treatment all will be good, better than a seized motor thats for sure
pete

[Honda Al]

Hi James,

Out of curiosity how did you get on with this?

Alan

[JamesH]

Hi Alan. I'll let you know this evening - have let the windings soak for a few days. Going to remove the rotor tomorrow and leave to soak in the same fluid for a few days before checking for clearances etc...

[JamesH]

5days of soaking in Metal Rescue...not bad at all!!

[ST1100]

Now I'd apply some ACF-50 on the stator and parts for conservation...

[Green1]

Impressive I expected the glue to breakdown soaking in that rust remover.

Mick

[AshimotoK0]

Impressive I expected the glue to breakdown soaking in that rust remover.

Mick

Stator has epoxy coating and magnet wire coating is pretty tough, should be OK.  Your problem will be if the rust has abraded through the magnet wire coating, as it did on 2 of my 400/4 stators that were only about 8 years old at the time. Just do the test I detailed earlier.

Currrently rewinding two Harley Davidson 50 Amp stators at work with both PEEK coated wire and PTFE coated wire, as we are running a test in some nasty aggressive refrigerant at 150 Deg C. for a project. Bike alternators seem to be permanent magnet rotors these days, must be the advances in rare-earth magnets, that were not around in the 70's