good deal or not clutch parts help in identifing what I bought please

[cruzin]

I responded to a close by craigslist for sale add. It was for a xs650 clutch for 10 bucks, and another 15 for a unused set of 6 Barnett clutch disks.
In the clutch it has 6 disks and I dont know haw many friction plates and on the back it has 6 springs on the inside. There are markings on the front of the clutch K.D.C. and 34101.
The unused disks are marked BT&E YPK-4. I see they are used in some 650's but I do not know what years. Ive included pictures but not sure they will post as my phone takes pictures that are over 2 meg each.
Any help to let me know what these are would be appreciated. Ive got a 76 xs getting ready to finish it up and would like to know if I should put the Barnett plates in. thanks

 

[azman857]

I think you will need one more clutch plate.

 

[5twins]

I think you got a very good deal. If the clutch only has 6 friction plates, it is probably the last clutch style used, from about 1980 on. One of the friction plates was removed so that a spring-loaded steel plate could be added at the bottom of the stack. This dampens the engagement. Personally, I like this clutch pack better than the middle 7 plate style you have in your '76. That damper plate eases the strain on those 6 springs on the back of the hub. They can and do break after many miles and/or abuse.

This whole later 6 plate style will swap into your '76 or you can just use parts of it. Any will swap in - the outer hub, the inner 6 plate hub, or any of the plates. The steel and fiber plates are the same as yours. The only plate that differs is that bottom spring-loaded one. It is slightly thicker than the other steels.

Barnett lists two different clutch friction plates for the 650 although I'm not sure why. They list those YPK-4's you have for the '74 model and YPK-5's for '75 and later models. This doesn't make sense because the '74 model used the same plates as the later models. The retail price on these plates is about $15 each so getting 6 for that is a very good deal.

 

[TwoManyXS1Bs]

...Barnett lists two different clutch friction plates for the 650 although I'm not sure why. They list those YPK-4's you have for the '74 model and YPK-5's for '75 and later models. This doesn't make sense because the '74 model used the same plates as the later models. The retail price on these plates is about $15 each so getting 6 for that is a very good deal.

Yes, this needs close scrutiny. Those pictured plates, and the Barnett tag, look a lot like what I acquired back in the '70's, and may be the old/NOS plates for the 70-73 6-plate clutch. You'll need to measure the thicknesses of those plates.

3.5mm (0.138") thick will be the 70-73 clutch.
3.0mm (0.118") thick will be for the later clutches.

To use the 3.5mm frictions, you'll need the 1.6mm (0.063") steels.
To use the 3.0mm frictions, you'll need the 1.4mm (0.055") steels.

 

[TwoManyXS1Bs]

..This whole later 6 plate style will swap into your '76 or you can just use parts of it. Any will swap in - the outer hub, the inner 6 plate hub, or any of the plates. The steel and fiber plates are the same as yours. The only plate that differs is that bottom spring-loaded one. It is slightly thicker than the other steels...

I looked up that thicker steel plate, and whattaya know, it's the same 256 part number as the 70-73 steels.

 

[TwoManyXS1Bs]

I have a suspicion about the 80-83 clutch that someone else would have to confirm.

Since it uses that dampened thicker plate in back, and the service manuals show a longer free-length for the clutch springs, AND the pressure plate is embossed with a '341', instead of a '447', I"m thinking that the pressure plate may have deeper spring cups, making it a 'match only' with the 80-83 hub.

Something to watch for with frankenclutches.

Does that make sense?

 

[cruzin]

Thanks guys for all the reply and info on the clutches. Ive got some reading to do on the clutches. Its going to be a few weeks down the road before I can actually get started on the bike again. Got to get the 2-up bike ready for the season. thanks Ill mic the disks and get back in here on this.

they mic out 3.55mm

I will check the disks and see if I can use these.

 

[5twins]

It's funny, Barnett doesn't even list plates for the '70 to '73 models but obviously, the YPK-4's are them. My take on the newer longer springs is that Yamaha probably decided to use a slightly stiffer spring when they eliminated one of the friction plates.

The "341" pressure plate is the only one listed for '74 and newer bikes. I have some "middle" and "late" clutch assemblies. I'll have to take a closer look at the pressure plates. I thought they were the same but maybe not. Most aftermarket springs are 40 to 42mm long and they do fit/work in the "middle" clutch assemblies so I don't see the need for Yamaha to change the spring cup depth for their later longer spring.

 

[TwoManyXS1Bs]

It's funny, Barnett doesn't even list plates for the '70 to '73 models but obviously, the YPK-4's are them...

Sure looks like it. Those could be rare collectables, or useless relics.

My take on the newer longer springs is that Yamaha probably decided to use a slightly stiffer spring when they eliminated one of the friction plates.

The "341" pressure plate is the only one listed for '74 and newer bikes. I have some "middle" and "late" clutch assemblies. I'll have to take a closer look at the pressure plates. I thought they were the same but maybe not. Most aftermarket springs are 40 to 42mm long and they do fit/work in the "middle" clutch assemblies so I don't see the need for Yamaha to change the spring cup depth for their later longer spring.

I've found 256, 447, 341, and 1T3 part numbers for the clutch assemblies. Up to rev -09 for the 256, up to rev -01 for the 447. Most of my data collection is for the 256's, not enough covering the later models, still learning about those later types.

I acquired a couple of clutch assemblies awhile back, in preparation for upgrading (I like the splined hub/pressure-plate interloc design). Dug one of them out and found a '341' emboss on the pressure plate of a '447' assembly. Here's the kind of measurement I was thinking of:

It's also possible that the spring posts in the hubs are different length, to accomodate the different clutchpack thicknesses, which could render the pressure plate issue moot. The measurement there would be from rear surface of hub to the end of the spring posts (which establishes the seating depth of the spring spacers). But, I'm getting ahead of myself, haven't done enuff research, and this is 5Twins' area of expertise, so I'll go stand in the corner for now...

 

[5twins]

I'm by no means an expert, I just happen to have a box full of clutches, lol. I did swap the later 6 plate unit into my '78 and quite like it. The original always let out with a bit of a "clunk" when taking off in 1st. This later unit engages smooth as silk.

 

[cruzin]

I havent taken this clutch apart yet. May be this weekend Ill see whats inside of it. The screws that hold it all together look in good shape not like mine were all chewed up before I replaced them.
Oh I looked this morning before I took off for work, yes I still work, my clutch has 7 friction disks in it. So I guess those steel plates would be the thinner type. , hey I like that "6 pack." I have a 80 or 81, the year they had mag wheels with drum brakes that I took on trade a couple years ago. I wonder what clutch they have in them. Havent even touched the bike yet. the motor is on a rack and rest of bike out back.

 

[5twins]

An '80 or '81 should have the later 6 plate style clutch. If that bike is just for parts, you might want to swap it's later E type cam chain tensioner bits onto your '76. The '76 D type tensioner had no lock nut. This can cause problems after an adjustment when re-installing the cap nut. It can change your adjustment, making it tighter. This can lead to premature cam chain stretch.

 

[cruzin]

I took clutch apart today and found that it has 1.4 mm steel plates in in. Now this clutch has the small wire that goes around the pack would I need to put that wire in my hub if I were going to change it all to mine. My isnt rusty like this one is. Of course I could clean it all up also.

 

[txxs]

Some of the posts indicate that 70 - 73 clutches are in a common group. This is not strictly correct.

70 is slightly different from 71. (70 does not have the ring cushion).
71 & 72 are the same.
The 73 clutch is slightly different in that two of the friction plates are "341" and the remaining four are "256".

Just want to clarify this point.

 

[cruzin]

I think you got a very good deal. If the clutch only has 6 friction plates, it is probably the last clutch style used, from about 1980 on. One of the friction plates was removed so that a spring-loaded steel plate could be added at the bottom of the stack. This dampens the engagement. Personally, I like this clutch pack better than the middle 7 plate style you have in your '76. That damper plate eases the strain on those 6 springs on the back of the hub. They can and do break after many miles and/or abuse.

This whole later 6 plate style will swap into your '76 or you can just use parts of it. Any will swap in - the outer hub, the inner 6 plate hub, or any of the plates. The steel and fiber plates are the same as yours. The only plate that differs is that bottom spring-loaded one. It is slightly thicker than the other steels.

Barnett lists two different clutch friction plates for the 650 although I'm not sure why. They list those YPK-4's you have for the '74 model and YPK-5's for '75 and later models. This doesn't make sense because the '74 model used the same plates as the later models. The retail price on these plates is about $15 each so getting 6 for that is a very good deal.

5twins what do you mean bottom spring loaded one? Is that the small wire going around the pack?

 

[5twins]

The small wire is part of it. That's what retains the plate, it's "spring", and a thin spacer washer. The assembly is parts 6 - 9 .....

The "spring" is a large Bellville type washer ring. It doesn't give the steel plate much spring-loaded movement, maybe a MM or 2 at most, but that is enough to smooth the engagement of the plates. The steel plate is a little thicker than all the others @ 1.6mm. It is actually one of the steel plates used in the early '70 to '73 clutches, as 2Many mentioned.

If you remove all the loose plates, you can see how that wire works. It fits into a groove in the hub teeth and stops each plate tooth from sliding out .....

The ends of the wire have loops on them and are bent over. These snap into a hole in the hub to retain the wire. Pop them out and you can remove the wire, then all the damper plate parts .....

Like I said, I like this later clutch pack and it would be my choice if I needed to replace an older unit. You can swap just this inner hub into an older outer hub, at least back to '74 anyway. No need to swap in the entire assembly.

It's nice that all these clutch parts can be swapped, mixed, and matched. As I also mentioned earlier, those 6 damper springs on the back side of the main hub can break over time, extended use, or abuse. There is a kit to replace/repair them but it costs near $50. I found it cheaper just to buy whole used clutches. Besides the outer hub, you'll also then have spare plates, springs, etc. You used to be able to find them on eBay for $20 to $30 but they are going up. You did good getting one for $10, and if it's the later 6 plate unit, all the better.

 

[cruzin]

After closer examination and taking apart I found just what you described. Now that I have it apart I can not remember if that dished spring goes with the dish up or down or dont it matter. Ill look further in the clutch part of forum and see if I can get some close up or instructions on re assembly

 

[5twins]

I don't have any good pics of that. The high part of the dished washer, which I think is the I.D., faces in and rides against the spacer washer which has a little lip on one edge, the I.D. I think. Anyway, the high part of the spring washer fits against the lip edge of the spacer washer. The high edge of the spring washer facing in can be either the O.D. or I.D., depending which way you flip it over. Make it match up to the lip edge of the inner spacer washer.

 

[cruzin]

update, by examination of the spring plate and thicker plate I can see that the spring plate has wore a small grove around the thicker plate. It is just a line around it and can feel the grove with my fingernail. I wonder if I should flip the thicker plate over and get a fresh start with the wear? any thoughts? and thanks for the help 5 twins

 

[5twins]

I suppose that wouldn't hurt. Never noticed that on any. I'll have to look for it from now on.