No doubt, you’ve heard about my starter clutch bolts coming loose on their own. It’s a popular post on this site, so it might even be why you are here in the first place. For that problem, I have always maintained that starter clutches like the ones installed on the 750 (just like countless UJMs) are just little disasters waiting to happen (pins/boss wear, spring failure, etc.).
But for this post… Nope, this was all my own fault. Let me explain…
Back in 2003 when I bought this 750, the stator was no good. It looked good cosmetically, but must’ve been damaged internally; because it failed tests as described in the Kawasaki Service Manual. So, I had a replacement shipped from a reputable vendor, and I’m pleased to report that the stator *itself* is still going strong almost a decade after the replacement.
But, *I’m the one* who bolted it in. And apparently (though I don’t remember), I must also be the one who didn’t bother with the LocTite that day. Because for the last month or so, I started hearing a rattling in the starter clutch area. Thinking it was loose starter clutch bolts again, I tore it apart and looked. To my pleasant surprise, the *red* (yes, red) LocTite I put in place on the starter clutch bolts (remember, there are no innards in my starter clutches any more) are still firmly in place. So I gleefully re-assembled, and assumed I misdiagnosed the noise (like it might be a cam chain slipper or something).
I rode it for a couple more weeks until the noise got loud. By the time I got home, it was a scraping sound. Great, I figured a piston ring on the left side had gone belly up. But on a hunch, I went back in to the starter clutch cover…
…and this is what I found. With the stator cover removed and in my right hand, I looked at the starter clutch again, and again, nothin’. This time though, I actually caught a glance inside the stator cover and… Whoa! The allen bolts were coming out!
The most frustrating part is that I must’ve looked right past them a month ago. Upon closer inspection, one of the bolt tops was getting rounded off! The other two were loose, but otherwise fine. Note the metal “paste” that had resulted from the wear. Fortunately, it’s a magnet, so the metal paste elements didn’t go far. I was still going to have to change my oil and filter anyway…
You can see the wear and scrape marks where the bolt heads wore against the rotor inner wall (and the tips of the starter clutch bolts). But hey; you can see the starter clutch bolt tips still firmly in place…
How pathetic is this… One of the bolts (the worn one) was completely loose and pulled right out. This could have been disasterous if it got caught against the rotor!
Oh well. Like I said, I re-assembled with Blue LocTite this time, changed the oil and filter; and after a test-ride all is well again.
It could have been much, much worse… It could have been like my starter clutch failure…
I had my starter clutch bolts come loose on my ’76 B-1. It sounded like a rod knock! But it was those nasty bolts that I didn’t thread lock. It’s O.K. I got my chance to install my freshly bored motor installed (.75mm). Now its jet time 125 is way too lean. I found larger jet at “mikes xs”, yes Yamahas share the same lovely 38mm Carbs.Glads it was a simple fix for ya!
Yep, loose bolts in an engine are definitely a bad thing… 😉
And you’re right about 125 being lean.. to lean for stock even, in my opinion.
I like Mike’sXS too… Good site/vendor…
my kz750 is a1977
my kz750 is a1977
@ Charlie –
The starter clutch is likely at fault here. It has 3 pins, 3 springs, and 3 rollers. If the starter won’t stay engaged, sometimes it is due to imperfect surface areas on the shaft, and the rollers can’t grab when trying to start. The imperfection can me microscopic. I read once in the forums a long time ago that someone turned the shaft in a lathe (where the starter clutch grabs) and it solved the problem. Sometimes it’s the rollers themselves. If it worked before and now doesn’t, it might be that the rollers prefer to be in a different order. I wish I had more ideas, but as you can plainly see in the article above, I haven’t pushed a starter button in a decade or so… It almost always start with one kick! 😉
Got them bolts spinning out even with loc tite n a ton of torque. Welded the clutch on the flywheel and no more bolts needed. The pins and springs are still well accessible too.