Yamaha XS650 Experimental Clutch, version 2.0

Oh, it functions very nicely, just the same as the version 1.0 clutch (after I got its internal clearances set properly), as posted in this thread from last year:

http://www.xs650.com/threads/yamaha-xs650-experimental-clutch.47498/

Ever since then, I've never experienced the dreaded 'stuck clutch' syndrome, requiring one to kickstart with the clutch lever pulled in to free the plates. And the dreaded 'clunk' (possibly followed with a 'lurch' and engine stall) when entering 1st gear. It just goes 'snick' when entering 1st.

With the engine idling, clutch lever pulled in, and in 1st gear (or any gear for that matter), I can roll the bike fore and aft, just as easily as if it was in neutral...
 
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WOW.... are you sure you weren't a watchmaker in a previous life 2M ???? My word man ! that had to take untold hours to do !
the accuracy alone is mine boggling all of those little holes...all right on the money ? Geeze ! I wish I could do that ! LOL
Well done Sir !
Bob.........
 
Splendid, indeed.
Just think of how things might have turned out differently if you were working with the Yamaha Engineering Development Team in 1968.
 
Ok quick question 2M..... what keeps it from sticking like the original setup ?...... why doesn't it stick ?
Bob.......
 
... are you sure you weren't a watchmaker in a previous life 2M ????

Haha, thanx, Bob. Back when I was a kid, I'd fix other kids' pocket and wristwatches. Must've had a permanent influence.

Ok quick question 2M..... what keeps it from sticking like the original setup ?...... why doesn't it stick ?

Bob, I'm sure that it still sticks. But this "spreader" thing spreads the plates, unsticking them. So, it's not preventing 'sticking', it's unsticking them by pulling them apart first.

I don't recall this stuck or sticking clutch thing being much of an issue back in the '70s. Now it is. Other forums I've seen report the same stuck/sticking on other bikes. But, it doesn't seem to be universal issue, not occurring to everybody, only the chosen few. Strange. I've read others' reports of the plates feeling sticky, and experienced the same myself, like handling flypaper.

There's numerous postings blaming this stickyness on the viscosity modifiers of multi-vis oils. I really have no answers, just listening to the banter...
 
Splendid, indeed.
Just think of how things might have turned out differently if you were working with the Yamaha Engineering Development Team in 1968.

Oh, my. 1968? I had just finished inventing an aircraft ID computer, started work on an ion-propulsion project, then discovered, of all things, .........girls!

That was a crazy time.

There were those that claimed that my projects were really booby-traps in disguise. Dunno. If I had been involved in Yamaha's projects, they could've easily been deep-sixed from my involvements...
 
Yes... too hard to reproduce for mass production and other such excuses ! LOL
another question 2M ! ..... when feathering the clutch allot like trying to get un stuck from a muddy creek or something like that that you've had no brains and gotten yourself into !.... will that ware on a single clutch plate ? I believe it would have on the original design because it takes the path of least resistance... is this going to be the same with this mod as well ?
I still don't understand how you've accomplished the pulling them apart method which is shear genius ! but I LOVE IT!
Bob.....
 
Yes... too hard to reproduce for mass production and other such excuses !

Haha, yeah, like trying to mass produce basket weaving.
I suppose that much more sophisticated and expen$ive jigs and fixtures could be built for the drilling/tapping tasks, but you'd need a large audience to justify that.

... when feathering the clutch allot like trying to get un stuck from a muddy creek or something like that that you've had no brains and gotten yourself into !.... will that ware on a single clutch plate ?

Yup, a lotta feathering/slipping of the clutch while negotiating life's challenges produces a lot of *heat* in the clutchpack, burning plates and oil. Pressures applied to a multi-disc clutch are not single-plate focused, but spread uniformly to all plates. But, due to position (heat dissipation) and whatever oiling is going on in there, one plate will likely succumb first. Our clutches don't have their own dedicated inner oil feed, like found on other bikes and auto transmissions. Ours get a tiny amount of their oiling from alongside the mushroom pushrod, and most from access holes in the pressure plate, which feed to the hub cavity, then out thru holes in the hub wall. I believe that improved oiling in the clutch is warranted...
 
I agree with the Improved oiling idea and think that would cure a bunch of clutch woes in the process....
but where does one start sense it's primarily a "Splash oil " system... could drilling a series of holes in the clutch basket improve oiling ?
without weakening the basket web too much so the friction disks don't push so hard as to break the metal off ....? I thought about doing this ages ago, but never did for fear of destroying the clutch basket... but I was thinking of say 3/16" holes on every web coming up from the basket that the clutch plates slide into , just to allow more oil in and out of the clutch stack.... I would think it would keep it cooler in operation and better lubed in all..... your thoughts ?
Bob......
 
Well, this is a little long-winded, but I'll share what I've been thinking.

The 70-73 '256' clutch pressure plate and hub don't have oiling holes. Those holes were introduced in the 1974 '447' design. So, it seems that mamayama was addressing some clutch issues with this change.

The pressure plate has oil introduction holes alongside the pressure plate's strengthening ribs.
ClutchOiling01.jpg


Those oiling holes emerge outward from there to the hub cavity.
ClutchOiling02.jpg ClutchOiling03.jpg

That oil goes into the hub cavity, and finds its way to the delivery holes in the hub wall, which then enters the clutch discs.
ClutchOiling04.jpg


The clutch basket spins as the engine is running. Any oil contacting the basket will be flung off, and can't enter the clutchpack, unless the engine is off.

Because the clutch basket is driven by the crank's primary gear, its rotation is backwards, CCW.
ClutchOiling10.jpg ClutchOiling11.jpg
 
So, the idea here is to get oil to the central zone of the pressure plate.

This pic of the XS650 oil system depicts where the oil level should be. I believe that it normally is a little below that.
ClutchOiling20.jpg


That oil level is about at the edge of the pressure plate's oil introduction cavity. If the pressure plate is spinning, there's little chance of oil getting in there.
 
The clearance between the pressure plate and sidecover is precious thin. Even less when the pressure plate is displaced outward (clutch disengaged). And, when the clutch is disengaged is when it needs the oil.

Excerpts thanx to Hans Pahl's engine cutaway pictures.

ClutchOiling30.jpg ClutchOiling31.jpg ClutchOiling32.jpg ClutchOiling33.jpg
 
So, the thinking here is that although there's provision for oiling the clutchpack, the ability for oil to actually get in there may be near non-existant, unless the engine is off, or the pressure plate isn't spinning. Maybe leaning the bike to the right, while stopped, in gear, clutch pulled, would allow for some oil to weep into there.

A good experiment for those experiencing difficulty finding neutral...
 
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Using that concept, I'm contemplating a similar 'windage scraper' mod to the right sidecover, using the top cover screw web as the backbone for a scraper. The collected oil would be diverted, somehow, to the central zone of the pressure plate, perhaps thru a groove...

ClutchOiling50.jpg
 
That oil level is about at the edge of the pressure plate's oil introduction cavity. If the pressure plate is spinning, there's little chance of oil getting in there.
You think the pressure lube system has enough reserve flow capacity to support a spray tube directed at the pressure plate holes? Wouldn't take much....
 
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...and a pressure passageway is pretty close to the clutch anyway...
 
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Well, I thought about cutting some grooves in the mushroom pushrod, to allow system oil pressure to deliver in there.

ClutchOiling60.jpg

I don't want to starve any tranny stuff downstream of that, but my high-volume oil pump shows pressures that should handle that.

What about those who show nearly zero pressures?
 
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