YZ-426 clutch problem (still)


11 replies to this topic
  • gscx

Posted May 16, 2012 - 08:37 PM

#1

I just put in a new Barnett clutch basket because I had problems with the one I had before (Barnett sent me a new one, no questions asked, awesome company). Before I took the old clutch out I had a cushion spring wear through the back and I knew when it happened because I heard a loud pop and the clutch made a whirring noise, I stopped. The noise went away and rode it the rest of the day no problem, then when I checked it later I saw the damage. But when I was loading it up to take to my shop it had trouble finding neutral, but the clutch was not dragging or anything weird, I found neutral easily with the bike off.

So when I put the new clutch basket in I reused my Barnett plates, that measured with spec. Put everything together and my clutch drags horribly, when I put it in first it jumps and stalls out. I ride it for a bit and the problem gets worse when it warms up. So I put in a new clutch (TUSK brand), but re-use the Barnett springs and it gets better. I can ride it without stalling when hitting the rear brake, but it still drags a lot. It will keep moving forward when the clutch is pulled in, cant find neutral when running, and the other symptoms of a dragging clutch. Anyone have any ideas? This is something that is really burning me up because a clutch isnt that difficult to fix.

The things that I have checked

- New basket
- New plates
- Inner hub isnt notched
- Pressure plate isnt warped
- When I pull in on the clutch lever the pressure plate lifts up evenly and about quarter of an inch
- obviously the cable free play is fine

I am going to try to put the springs that come with the TUSK kit in tomorrow and see if it fixes it. I have searched through the forums and nothing that I see will help me. Thank you for any help, because right now I am at a complete loss as to what to do.

  • RasmusDK

Posted May 17, 2012 - 04:57 AM

#2

if you over tight the center clutch it can drag, be sure that is ok. the manual says to tighten it around 50 fp or 67 nm. I think thats alot tho, I gave mine 40 nm. Brand new steel plates take time to break in, if you only took it for a quick spin like 5-10 min, give it a good hour to break in.. Being a bit evil on it gets you there faster =)

  • grayracer513

Posted May 17, 2012 - 08:18 AM

#3

I don't like Tusk and other lower cost aftermarket plates. One reason is that they often act up when hot, requiring constant tinkering with the cable adjuster, and another is that they tend drag a great deal more when freshly installed, and take a while longer than normal to get over it. (it's the frictions that are the problem most often). Rasmus is right about having to "burn in" the clutch.

But if everything is in good shape, the torque on the main shaft nut won't affect anything until it's either loose or strips the threads.

I also don't like aftermarket or "heavy duty" clutch springs, but you might closely check the spring set you have now for inconsistency, or swap them out for the other set. One weak spring will tip the pressure plate on release, which can cause your exact problem.

  • RasmusDK

Posted May 17, 2012 - 10:54 AM

#4

I have seen a center clutch that was tighten with an air impact wrench way to hard, the result was draggin, it could barely spin.. it was an old kawasaki tho, not sure if its possible on a yamaha, but it will never happen to me :cry:

  • gscx

Posted May 17, 2012 - 12:31 PM

#5

Well I just switched out the springs and the problem still persist. Tonight I am going to take it completely apart and look at it, but right now I have NO idea what it could be. If there is anything else that could be wrong just throw an idea out.

And I completely agree with you grey about the cheap clutch, I just had it around as a spare in case something happened at a race or something. But I doubt this is a "burning in" issue. As the barnett I had in before it that was used did the same thing. Ill tke a look tonight a little deeper and see what I can find.

  • grayracer513

Posted May 17, 2012 - 01:44 PM

#6

May not be related to the clutch. See if the main shaft and boss will turn freely in the basket/gear assembly. If some part of the driven gear bearing/cushion assembly was damaged so as to prevent the driven gear from spinning freely on the shaft, it's possible that is the cause.

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  • gscx

Posted May 18, 2012 - 10:44 PM

#7

Well I cant visibly see any damage, but that doesnt mean one is there. In desperation I have ordered a used 2001 clutch basket from ebay to see if that fixes the problem. If it does then I know that something is wrong with my driven gear and in that case I will have one to put on my new barnett basket. If it doesnt work then I will go by process of elimination.

  • gscx

Posted May 21, 2012 - 07:43 PM

#8

Well I got the used basket and this is what I found. When I put it on there was no difference, normal. So I go to put my inner hub on and I tighten it down. When I get it tight ( I don't torque it, as I use a air gun, but I don't think it is above the spec) The inner hub wont spin freely, it is rubbing on something. I put paint on the back of the hub to see where it was rubbing at and there weren't any marks on it when I took it off. So I guess now I am going to get a new inner hub and go from there. Hopefully that works because If it doesnt then I am truly out of ideas

  • grayracer513

Posted May 22, 2012 - 06:59 AM

#9

The space allotted to the driven gear bearing is too short. Sort of obvious, I suppose, and the question is why. The thrust washer that runs between the basket and boss (hub) is OK, yes? And you don't have a washer/shim/spacer of any kind behind the basket against the bearing?

Put the hub on the main shaft without the basket and see what the hub stops against as it slides on. Check that area of the shaft and hub to see if it's been compressed.

  • gscx

Posted May 22, 2012 - 07:40 AM

#10

I also got a thrust washer with the basket. So im going to assume that it is the right thickness, unless the bike it came off of had the same problem. And I dont have anything in there that doesnt belong, maybe the inner hub got compressed for some reason? When I put the basket on The shaft came level with the bottom of the gasket (the part that the thrust washer rides on). And When I put the inner hub on by its-self it rides on this part. There is something off by not even quarter of a millimeter, beacuse when I really torque it down I can spin it with my hand. Even though it is pretty hard. The driven shaft doesnt look damaged in any way. There is also a little bit of back and forth freeplay in it so its not bound up inside or anything weird. And the transmission shifts fine. I will take some pics when I have it apart again tonight. Do you think that posting in the engine forum would help also? Or would this be a YZ specific problem?

  • grayracer513

Posted May 22, 2012 - 09:47 AM

#11

The engineering forum? No, not really. Kind of off topic. You don't have a 2000 model with some '01-'02 parts blended in, do you?

Any chance it has the wrong clutch hub?

The clutch hub needs to bolt down against the main shaft in such a way as to leave a space behind it on the shaft that's as long as the basket center bearing and the thrust washer, plus some clearance.

Of course you already know that the basket assembly has to mesh with three gears in order to sit all the way back where it goes; primary gear, kick idler, and oil pump idler.

  • gscx

Posted May 22, 2012 - 12:31 PM

#12

No its all 2001 and 2002. The hub is the same one that was in it when it started acting up. So I think I will get a new one, and go from there. Because right now i cant see anything else being the problem. For now I have the nut kind of tight and it will stay on and it runs fine. No funny noises. But I will fix this when I get the money to buy a new inner hub.





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