Separate Rotor From Starter Clutch

[Azul the Cat]

I've got a '77 GS750 where there starter clutch seems to be frozen onto the rotor. When the bike would start, you would hear the starter motor still spinning, so I turned it off right away. Tried again, and same deal. After a bit of research I figured my starter clutch needs to be rebuilt so I get the bolt from Motion Pro to pull the rotor assembly off the shaft. No problem there, but how do I get the starter clutch itself apart from the rotor? Nothing wants to move, and I can access the 3 bolts in the starter clutch behind the starter gear. Any ideas, or do I need to look for a whole new assembly?

[Steve]

When you pull the rotor off the end of the crank, BE CAREFUL, there are three rollers, three pins and three springs that are anxiously looking for somewhere else to be.

Once you get the rotor off, you will be able to see the three screws.

.

[Azul the Cat]

Thanks I'll be careful when I get the rotor off. That's my problem though, I can't get the rotor apart from the clutch. I got the whole assembly off of the crankshaft no problem. Do I need the slide hammer tool to get the rotor apart from the clutch? I checked the service manual on BassCliff and it seems like they should come off in separate parts. My Haynes manual talks about the using the swing arm bolt and a big socket, but I figured doing it that way would do the same thing as the puller from Motion Pro. Here is what I have now, it's all one unit.

20200525_060914 (Medium).jpg

[Azul the Cat]

So i got them apart from each other. I put the whole assembly back on the shaft and loosely put the bolt in to hold it in place but still have some wiggle room. I wedged my big flat head screw driver in between the starter gear and the clutch and lightly applied force moving around the outside till it popped off. One roller in the clutch popped out like you said, but it fell down the hole so it didn't go anywhere. Surprisingly all the rollers, pins, and springs look to be in really good shape, and the rollers travel freely. So I cleaned everything up and put it back together.

[Dogma]

The screw heads are behind the gear. Steve misspoke with his fingers when he wrote that the rotor covers the screws. The gear should come off by hand, or even fall off. Everything else should stay captured until you get those screws out and separate the clutch from the rotor. Here's where's Steve's warning about springs comes in. But your symptoms suggest something else is going on.

The rollers of the clutch engage on the gear's hub, so if your starter clutch is jammed somehow, you're going to have a hard time getting that gear off. Hopefully the surface of the gear's hub isn't damaged. There isn't much leeway for regrinding that surface before it's too small for the clutch to work. The rebuild kits come with new rollers, so I hope all the damage is there or in the pins.

[Big T]

Take a good look at the part of the gear that goes into the starter clutch
It should be smooth and round. My starter clutch failed slowly, and when I pulled the gear, it looked like the 7 dwarves had been hammering on it

[Azul the Cat]

The screw heads are behind the gear. Steve misspoke with his fingers when he wrote that the rotor covers the screws. The gear should come off by hand, or even fall off. Everything else should stay captured until you get those screws out and separate the clutch from the rotor. Here's where's Steve's warning about springs comes in. But your symptoms suggest something else is going on.

The rollers of the clutch engage on the gear's hub, so if your starter clutch is jammed somehow, you're going to have a hard time getting that gear off. Hopefully the surface of the gear's hub isn't damaged. There isn't much leeway for regrinding that surface before it's too small for the clutch to work. The rebuild kits come with new rollers, so I hope all the damage is there or in the pins.

When you say the gears hub, do you mean the crank shaft coming out of the engine, because that had some light scoring on it. Everything else looked pretty good.

Take a good look at the part of the gear that goes into the starter clutch
It should be smooth and round. My starter clutch failed slowly, and when I pulled the gear, it looked like the 7 dwarves had been hammering on it

The whole gear looked pretty good including the part that went inside the clutch so that's a plus.

[Dogma]

When you say the gears hub, do you mean the crank shaft coming out of the engine, because that had some light scoring on it. Everything else looked pretty good.



The whole gear looked pretty good including the part that went inside the clutch so that's a plus.

I didn't mean the crankshaft, but it's interesting you point out scoring there. The gear should run freely on the crank. The 1000G even has a roller bearing there. Scoring there suggests oil deprivation. I was wondering why a starter clutch would lock up.

Like Big T pointed out, it's the part of the gear that goes into the clutch you should be examining. ("Hub" is engineer lingo for the feature that mounts a part onto a shaft, like a wheel hub.) If the crank is scored, you should probably examine the inside diameter of the gear as well.

Did you get the gear separated from the start clutch?

[Azul the Cat]

Yep, I got them apart. I should clarify, no scoring where the roller bearing touch the crank shaft. It was at the very end of the tapered part of the crank shaft, close to where the bolt goes in. Maybe 1/4" - 1/2" in from the very end. Annotation 2020-05-28 062032.jpg

[Dogma]

OK. Only the rotor sits on the taper. Since it spins with the crank, some scoring there shouldn't be a problem. Now that you have the gear off and can get at the screws, what did you find inside?

[Azul the Cat]

All the rollers, springs, and pins looks to be in decent shape. The previous owner did say he had the magneto and rotor replaced. I wonder if they rebuilt the starter clutch and the whole assembly was maybe on too tight? Do I need to take the clutch off the rotor to fully see if it's working properly? When I put it back on by hand and turned the rotor/ clutch assembly, it seemed to be doing what it was supposed to do. It let the gear spin freely one way, but not the other.

[GregT]

All the rollers, springs, and pins looks to be in decent shape. The previous owner did say he had the magneto and rotor replaced. I wonder if they rebuilt the starter clutch and the whole assembly was maybe on too tight? Do I need to take the clutch off the rotor to fully see if it's working properly? When I put it back on by hand and turned the rotor/ clutch assembly, it seemed to be doing what it was supposed to do. It let the gear spin freely one way, but not the other.

If the mechanicals seem to be working as they should, go back to square one.
Have you got a sticky relay or starter switch ?
If the power to the starter motor doesn't cease when the start button is released, you'd have the symptoms you've described.

[Dogma]

If the mechanicals seem to be working as they should, go back to square one.
Have you got a sticky relay or starter switch ?
If the power to the starter motor doesn't cease when the start button is released, you'd have the symptoms you've described.

Good point. Since it's out, taking out those three screws to clean and inspecting the internals isn't a bad idea.