Topic: Poll: How many people have had bad stators?

[scottly]

I'm wondering how common stator failures are on SOHCs? Is this a common problem?

[Don R]

i never did

[77cafe750]

does answeering this question jynx one i have no trouble on "sarah" yet

[69modelj]

k5 750, 53000 miles, ok @this time

[754]

Do you mean the outer windings..??

 I had one, the wires all sheared almost simultanuosly,  right about the time my buddys right engine case, contacted my foot and dyno cover.... at 95 ish mph...

[BeSeeingYou]

Never had one yet and that's with 30K miles on an XS650, supposedly a common problem with that bike.

[MCRider]

It happens, not very common. More likely the 3 leads get old and brittle and break off. Hard to splice. That comes from lack of use, not from use.

[TwoTired]

SOHC4 Stator failures are quite rare, nearly never, if left on their own.  Yes, mechanical abuse such as a crash, axe, or sledge hammer can damage them.

They do not overheat on their own.  Their output is self limiting. If you overload the output, the AC peak voltage simply isn't developed as the energy is siphoned off before peak is reached, and this limits its output.  I believe you can short their outputs to ground and they still won't self damage electrically.

If you screw up the alignment of the rotor such that it contacts the windings, well that is mechanical abuse.
I don't think they will survive if you toss them over a cliff, either.
In short, I think they are far more robust than people give them credit for. 

Now the field coils are quite another matter, particularly of they are wound onto the rotor.

[scottly]

Do you mean the outer windings..??

 I had one, the wires all sheared almost simultanuosly,  right about the time my buddys right engine case, contacted my foot and dyno cover.... at 95 ish mph...

Geez, what happened to your foot!!??

[754]

 I broke about 8 bones in the middle of my foot, several were not fixable... I was young then.. healed up fast.. outa plaster in a few months... it got my thumb and elbow too, not so bad..

 Aftr that, the next  injury to that leg was a lot worse..

 

[scottly]

Ouch!! Don't want to hear anymore!! Your stator had a valid reason for its demise; may it rest in peace...
Anyone else (other than campbmic) have problems with a stator???

[dave500]

i bought 2 500 motors and 2 550 motors as a lot,,2 had open circuit stators,one dead field,,these had been used in go karts.,and they are getting old.

[scottly]

Thanks Dave, that's the kind of data I'm looking for. Were the bad stators from the 500s or the 550s, or one of each? Was the field open, as well?

[dave500]

yeah the field was open,one stator was burnt looking,,dont remember which motors they were from,,both the same really in that respect anyway.,ive been riding mine for 20,000 kays over 3 years,i dont think they are a problematic thing,,,or more would be posted to that effect.,if you come across cheap motors,take your multi meter when you look at them,,it might be worth it just for the electrics!!

[scottly]

i dont think they are a problematic thing,,,or more would be posted to that effect.

That's what I'm trying to find out; just how problematic it is. Say it's a 1% failure rate: if 100,000 units were produced, we would expect 1000 failures. In your case, you had two failures from four motors, equals 50%.

[dave500]

in my case yeah,,but overall they dont give any drama,,my 4 motors which were ex go kart ,which ill bet were ex wreckers motors in the first place,so they all came from a dubious source..i wouldnt agree that 50% fail.

[scottly]

Bump. Can anyone else report stator failures?

[MCRider]

Bump. Can anyone else report stator failures?

I had a failure 1/3 went away, an internal breakdown of wiring. Bike had been abused terribly (by me) dragraced, roadraced, crashed on the left side (at lest 2 replacement dyno covers) about 50k total miles. Only failure, I've got about 125,000 total CB750 miles.

Its very rare, compared to say the GS series of Suzukis. Its the least of my worries re: CB750.

It is not a problem that has a reputation attached to it.

[scottly]

Thanks MC, the 1/3 is relevant; I'm thinking these failures are due to breakdown of the varnish insulation, over time, exposed to motor oil and temperature...