Whats up with these clutch springs ??

YamadudeXS650C

Central New York XS650
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I'm doing a resto on my 1976C with 17K miles. It was running OK before I fully dismantled it. The clutch was functioning OK, too. I've just dismantled the clutch. The steel discs are OK and not warped, and the friction discs are worn only about half way. The clutch springs have me a bit puzzled, however. The stock length is supposed to be 1.362 in. Mine free measure from 1.658 to 1.668 in. This is about the length of the Vesrah springs that Mike sells at 650 Central. SO, it kinda looks like the PO replaced the stock springs with an aftermarket set (?).

The variance of .010 between the heights of my 6 springs seems to be OK with me, so I'm thinking of keeping them in there. I have no "original" height measure to compare them to, as to possible sagging, and who knows how long they have been in there. I'd appreciate any opinions. Replace? Run them? I'm disinclined to just throw new ones in there, if these might be usable.

BTW, the diameter of my springs is .655
The spring wire thickness is .091
 

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The '74-'79 7 plate clutch did use 34.6mm long springs. Apparently they were changed for the next generation 6 plate clutch that came out around 1980. I'm thinking they were possibly a little stiffer because of the one less friction plate. So, you may have aftermarket, or you may have later model stockers. I would try them, if the clutch slips, change them.

Nice manual excerpt TwoMany. Where did you get it?

Edit: never mind, found it
 
Nice manual excerpt TwoMany. Where did you get it?

Hey, 5T! That's from the cut-up, 7 part XS650SJ service manual PDF, chapter 7, I think from XScafe or biker.net?

I usually pull-up one of the downloaded PDF manuals, zoom into a particular area, then screenshoot.
Then bring the screenshot into Pixlar, tweak it a bit, add RED annotations, then save it in a smaller/mid-resolution forum friendly format...
 
Thanks for the input, guys.

I've also come across some informative replies to jkbiker's almost identical inquiry that he posted back in 2010. There was some good discussion by XSLeo of the color of the springs (painted).

Back in the early 90's I was in discussion with Tech at Barnett in regards to some tweeks done to one of their high performance clutches that I had on my modified '84 FJ1200 which had about 160hp, as I recall. Altho there was the usual emphasis on adequate spring pressure, they also placed a good deal of emphasis on minimizing variance between the springs (height, pressure). In fact, I found a distributor of Barnett springs who routinely opened up all his packages of the same spring part number, measured them, and repackaged the sets which were most equivalent.

Having read just about all of the clutch info at XS650.com (excellent stuff!!), it is interesting to find only an occasional mention of this variable.
 

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Now, THAT is the sort of excellent technical study that I thoroughly appreciate, TooMany ! I will pour over it, shortly. Coincidentally, I just came up from the workroom, before catching your post, after having arranged my springs in a coordinated pattern to spread out the variance in free spring height, as you mention. This is what I did with my Barnett clutch, way back when.

Thanks !
 
Yew betcha! This forum is chock full of buried dissertations from highly-knowledgable previous members. Trick is to find 'em, can be a bit tough, especially if the thread title is vague. Sometimes takes days of researchin'...
 
Im using this thread a bit since i didnt wanna start a new one.
I have the later clutch, 1981 bike. With springs on free length at 41-42mm.
Can i install shorter springs for the later clutch? without mods? Or machine up spacers to equal length of the old longer springs
 
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