Starter & Starter Clutch Issues

I've been battling some electric starter/starter clutch issues on my 1979 KZ750 for a while now. Each time I think I've got it fixed, the problem comes right back. I need some help brainstorming what might be going on.

The symptom is the very common gravelly, marbles in a tin can sound that these starter clutches make when they fail. But I've rebuilt the starter clutch (twice actually just to be sure) and the problem keeps coming back. I also replaced my flywheel as it had some wear on the surface that the starter clutch rollers contact and I thought that might be the problem.

Each time I take it apart and put it back together it works fine for a while, then the problem starts again. It's as if the bolt that holds everything onto the crank shaft is coming loose but I'm torquing it according to the spec in the manual.

Additionally the electric starter has started making a strange noise.



It spins up just fine, but makes a sort of screech when it stops. I've taken it apart, replaced the brushes and the bearing, added some grease to the planetary gear, and it still does it.

Has anybody encountered this before? Any ideas what it might be and whether or not it could be somehow related to the recurring failure of the starter clutch?

replace

To me that sounds like the planetary Gears, dry on their locating shafts. You should see some dry galling marks where that is grabbing like that. Once a gain I'd take apart the starter motor and inspect. Make sure the small stake pin fro the Sun Gear is in place and not allowing it to turn.
So you say that the clutch is also giving problems engaging? Even after all those new parts?

The planetary gears sound like a reasonable place to look.

When I was disassembling, the stake pin (or key) fell out before I had a real good look at how it was installed. And the manual doesn't provide much to go on. So I made my best guess and just wedged it in between the sun gear and the outer housing like a shim. Do you have a picture of where this goes?

Regarding the starter clutch, yes even after all new rollers, caps, springs and a flywheel it won't engage consistently. I've not replaced the starter clutch gear or the thrust washer, but they both appear to be in good shape. I'm torquing the bolt that holds all that on the flywheel to 101 ft. lbs which is the upper end of the spec in the manual. It'll work for a while, then it stops engaging.

Sorry Topper, I don't have a picture. I also don't have a Twin starter to pull apart. I looked on the net and you tube etc. Found several pictures/ diagrams/ and a few videos. None showing exactly where the Key Fits. But I can tell you that it goes in between the end housing and the sun gear, to stake it in place. As the Sun Gear Must be held in place, it can not slip. Otherwise the Sun Gear will spin in the end housing, and the starter electric motor will be spinning but the output gear will Not. So you engine will not spin over/ no start.
Wish I had a clear picture for you, but can't find one. Maybe one of the Twin owners can post up one for you? Otherwise you will have to look real close at it and figure where the Key Holds the Sun Gear.
Those Posts By 750Steve I added to your thread a few months back. He had the same issue, but found where it fit. I don't see where he posted a clear picture either.