Did I screw up my starter clutch repair?

I bought this bike ('82 KZ750 H3) last summer for pocket change and have spent the last several months riding and rehabilitating it. The electric start has always been iffy, it would engage for 1 or 2 revolutions and then disengage. This was fine during the summer when the bike would start right up. When it got colder, it became impossible to start with the electric start. I was sure it was the starter clutch, and so this winter pulled the engine off the frame and made numerous repairs, including the starter clutch with a kit from Z1E. I moved it outside today to try to start it up, and I'm having the same issue as before! The video linked below is what I'm hearing (yes it's snowing). The starter engages, then kicks off. The motor keeps spinning, leading me to believe the motor is fine.

drive.google.com/file/d/1gGxQuO5_p21m4Yi...Ysj/view?usp=sharing

My understanding from having pulled apart the starter clutch is that the motor will engage with the secondary shaft whenever it's moving faster than the secondary shaft, and will then turn the crankshaft. This is obviously not happening, as heard in the video, the crankshaft stops and the starter motor keeps moving. Unless I screwed up the installation of the start clutch pieces (unlikely, I believe), the only possibility I can imagine is that the starter idler gear unmeshes from either the starter motor or the starter clutch gear.

Does anyone recognize these sounds? I really don't want to dig into the engine again until I have a good idea of what might be causing this.

I'm not sure if this is true on the Kz750-four or if it was maybe the Kz750-twin...

But on some starters it's possible for something to let loose inside the starter motor so that it spins internally, but the output shaft of the starter motor does not turn. I think it has to do with a ring-gear coming detached inside the starter body. When the ring gear spins, the output shaft stops spinning, but you can still hear the motor's main shaft spinning. I think you have to disassemble the starter motor to check it.

Hopefully someone else will chime in who knows more about it.

How much did you replace? Only The rollers, springs and pins? The main gear or the housing that holds the rollers have given others problems when not replacing. Hopefully Loud is right and its something in the starter.

On my Honda, that sound is a sign of:

Bolts that hold starter clutch assembly together are loose (very common)
or
Roller 'springs' need to be replaced - not sure the Kawasaki clutch is similar to Honda's but if it is, those springs do loose their tension over time and need to be replaced.
or
Rollers need to be replaced (but have never had to do that yet).

I have a 750 four. I replaced the rollers, pins, and springs together. I also replaced the starter clutch allen bolts (the old ones were basically stripped), and loctited them in. Loud has made me hopeful that it's the starter, and I'll pull it off and look at it again when I get home. If I don't find anything, I think I'll pull off the oil pan and try to watch the starter gear and the idler gear as I turn it over, and hope I can get a better idea of what's failing.

I have a 750-four. I replaced the rollers, pins, and springs. I also replaced the starter clutch allen bolts (old ones were stripped), and loctited them in. Loud has made me hopeful that it's the starter motor, and I'll pull it off when I get home and see if I can spot anything. If not, I think I'll pull off the oil pan and watch the starter gears as I turn it over, and try to get an idea of where it's disengaging.

Thanks for the input!

For anyone with the same issue, and for my own memory: I think I managed to fix the problem, or have at least mitigated it. The issue was not with the starter motor, but indeed with the starter clutch. When I pulled off the oil pan I could see the starter gear turning, but the secondary shaft was still. I pulled apart the starter clutch and stretched all three springs and put them back in. I also shortened the allen bolts slightly, as I think they were sitting a little high and rubbing against the starter gear, causing the grinding noise (credit cb900f). Now that it's all put back together, it turns the crankshaft consistently, and doesn't seem to slip.

As for root cause, I once saw another forum post that indicated a dented starter gear (where the rollers jam up against) can cause slip. Mine was in fact dented, and not smooth. I think if I have problems in the future, I'll bring the gear to a machine shop and have it turned just enough to be smooth. It seems stretching the clutch springs has fixed it for a while though. It could also be that the springs from my starter clutch repair kit just weren't right, and didn't have a high enough spring constant.

TL;DR: stretch your springs

The starter gear should really be replaced as the surface is worn and causes this slip, stretching the springs will be a temporary fix, i have encountered this before on the 650, it's a common thing on these motors right from the first 650s up until the last variant 750s air cooled models.

kevski wrote: The starter gear should really be replaced as the surface is worn and causes this slip, stretching the springs will be a temporary fix, i have encountered this before on the 650, it's a common thing on these motors right from the first 650s up until the last variant 750s air cooled models.

Example:



Ed

I remember seeing that in another post, and you guys are right, stretching the springs was a short term fix: like a couple days short term. I found a complete starter clutch assembly (with new gear and clutch) from a KZ650 that should arrive soon. I wanted to replace the 3-roller design with the one way bearing design from the ZR750, but had trouble finding used parts, and the required new parts would cost quite a bit more than I was willing to spend. In the meantime I've been using a drill to turn the crankshaft nut near the ignition pickups to get it started, and that's working well. Even in the New England winter, it starts with 1/2 second of cranking. This bike has been so good to me except for this one very obnoxious issue.