Kz550 Oil level with clutch cover off

I thought I recall a thread where someone was worried about their oil level after a rebuild, but I can't find the thread.
In it he said he saw the oil disappear from the site glass after starting the motor (which we know is normal), but he was also seeing a lot of splashing in/behind the window.

I was doing some clutch experiments and had the cover off so I took some photos. (BTW, if you tilt the bike enough, you can swap the clutch and only lose a couple drops of oil.)

The animation (3rd image) shows what the range of the oil level would be when the motor is stopped, and on a level surface. You can see the bottom of the clutch pack is in the oil (just barely in the oil when at the lowest level), but should be almost out, if not totally out, when the motor is running.

Perhaps the splashing he was seeing was because the oil level was high enough to touch the clutch. Or maybe it's the secondary shaft gear, which sits directly behind the clutch. The secondary gear is probably in the oil at all times, as it is lower than the clutch.

I can confirm that oil level too high does lead to clutch slippage (as is stated in the FSM).

This is great info loud!
Thanks for taking the time to build graphics to help understand easier.

Ok. Enquiring minds want to know: what kind of clutch experiments were you undertaking in your lab?
Should we call you Dr. von Loudhvx yet?

Dr? Yeah right, I wish the experiments were something worth reporting, but basically I just ruined a set of steel plates.

My bump-start-only bike, obviously, is easier to bumpstart when the clutch is not dragging while pushing in gear. So that has been a goal since I put the bike together... make the clutch release fully. The shame is, it was already pretty good to begin with.

Well about two years ago, after an oil change, I overfilled the oil a tiny bit. It was at the top mark on the centerstand, but I didn't realize it went higher after coming off the center stand. So the oil was high. This causes the clutch to slip when it is bathed in too much oil, apparently.

Normally, on an electric start, the starter turns the secondary shaft, which turns the crank. The clutch is out of the picture. But with a bumpstart, the trans turns the clutch, which turns the secondary shaft. And with the clutch slipping, it is literally impossible to turn the crank. This only happened when the motor was hot. After cool down it would start fine.

I checked the clutch and played with the springs and actuator, but eventually I just lived with it, and after the oil level became normal, I probably didn't have the problem anymore. When the season cooled off I forgot about it.

Then last year it started slipping again, probably after I topped the oil off too high again. I took the clutch apart again determined to fix it. All of the disks had plenty of material. The spring tension was in spec. and I was shimming them to get way more pressure anyway, so it wasn't the springs. The only thing that seemed out of normal was the plates were super shiny. I've read on many boards to scuff the steel plates. So that's what I did, very lightly, with what I think was about 380 grit. (There is potentially a big difference between 600 grit and P600 grit, but that is another story.)

BIG MISTAKE. It didn't fix the slipping problem, and now it dragged like crazy and made shifting into first from neutral sound like a baseball bat hitting a 50 gallon drum of marbles. So I lived with it like that for most of last year, and rode my other two bikes more. At some point I used finer grit paper to smooth the plates out. That helped a tiny bit, but it really didn't fix it. I finally broke down and installed new plates, and reduced the spring tension gambling that the oil level was the slippage problem. This was on the 4th of July... over the years I've found myself working on vehicles on the 4th, more so than doing any other thing.

So that's when I took the photos... as long as the cover was off.

I test rode the bike last night for hours in the city. It was great. No slippage, not even a hint, even with reducing the spring tension. The clutch feels like brand new. When I bump start, it pushes in gear almost as if it's in neutral. That is great, especially when bumping uphill.

By the way I have some kz550 steel plates that I have now scuffed with 1000 grit, but didn't have the nerve to try out, if anyone needs some just to get by. They are not warped at all, and are now very clean.

The interesting thing is, the clutch was both slipping when engaged and dragging when disengaged. I thought one would work against the other,

Also, as part of the experiments, I learned how to shorten clutch cables, as mine was a little long due to the clipons.

I'll post the photos of that, along with the destructive tension tests, when I get a chance. The parts to do it are inexpensive, and the procedure is not too hard.

That's pretty fascinating stuff to be working on... So, given what you've learned about it all now; what is your personal opinion about the correct oil level (in the window) for our bikes? Sounds almost like being closer to the top (what I always thought was "best") is perhaps not at all in the end...

Vell Doktor, I sink you may get voted for entry into zee Mad Scientist's Klub just for delvink into ziss subjekt.
Kudos!

The interesting thing is, the clutch was both slipping when engaged and dragging when disengaged

I had that, it turned out to be one of the friction clutch plates had delaminated around a quarter of it's circumference. It felt almost like a fluid clutch on an auto car,

That graphic is interesting, I suppose when the motor is upright, running and oil system pressurised with a full oil cooler and plenty sloshing around the cams the level would drop a bit further. Like dry sumping, excess fluid drag and aeration of the oil is best avoided.

Years ago I saw an amazing power wheelie on a 550, he had it right up there and was shifting through the box from one junction to another nearly a mile apart! really incredible and sounds a bit unbelievable I know. I wonder what would be a safe wheelie angle on these to avoid oil starvation?

I used to like to have it at the top mark, but now I think I like it near the top, but with a clearly visible air bubble at the top. Maybe a pea-size air bubble or a tiny bit bigger.

Hard to say where the oil level would be during a wheelie. The level clearly changes while running, but during a wheelie how much more would get held up in the head etc.? A lot of variables. Will it spill out of the breather?