Clutch slipping YZ250


27 replies to this topic
  • Wierac21

Posted February 24, 2013 - 05:16 PM

#1

Now that I finally got the bike running, when I run out a gear it feels like the clutch is still partially engaged. but I can pull the lever in and it acts like it should (engine slows, and it just rolls on its own).I'll go down the road and shift through the gears without using the clutch and it sounds like its goin 100 mph but really goin 10. I pulled the clutch cover off, the plates and fibers all seem fine, springs seem fine, the pull at the lever is good too. I can't figure it out. I cleaned every plate with brake clean and put them all back in the right way.

It feels like I'm riding with the clutch 1/2-3/4 of the way in. I pulled the flywheel cover and the clutch seemed to be moving fine too on that side. I'm at a loss of what it can be. Springs work, aren't over-tightened, fibers and plates are in good shape and were cleaned, put fresh 15-40 rotella in it (which multiple people use), and still nothing.

Any other ideas? Could it be a bad tranny? It shifts smoothly and doesn't seem rough, the engine is very healthy sounding, the basket has a little bit of grooves but nothing serious.

Any help would be greatly appreciated.

Edited by Wierac21, February 24, 2013 - 06:10 PM.


  • adam728

Posted February 24, 2013 - 05:26 PM

#2

Title says it's not disengaging, but your description sounds like it's slipping.

If it's slipping you need to check a few things:
  • Clutch lever free play - if the cable is wound right tight then it can stop the clutch from fully engaging and cause slippage
  • Clutch plate thickness - just eye-balling it doesn't tell you how worn they might be.
  • Clutch plate flatness - warped plates can cause slippage, although you'd likely see signs of heat damage at the points of contact
  • Clutch spring free length - You'll never find a spring that "looks bad" by just looking, you need to measure the free length and see if they are sacked out.
  • Clutch plates in correct order?
  • Correct number of plates?


  • Wierac21

Posted February 24, 2013 - 06:12 PM

#3

I edited my title because I think you're right. I'll check the specs on the plates and fibers tomorrow. Thanks for the help. I'm okay when it comes to carbs and body stuff, but internals make me a bit nervous.

I also was wondering if a 426f set of fibers and plates would fit this basket? I have a set brand new in the box for my tard that I got cheap. Not sure if it would or not and ill search after this but if someone knew off the top of their head that'd be cool too.

Edited by Wierac21, February 24, 2013 - 06:13 PM.


  • Wierac21

Posted February 24, 2013 - 06:19 PM

#4

Just read this:

"I noticed with my bike i can control how grabby the clutch is by adjusting the main or centre nut of the clutch...tighten that nut till you can just barley turn the inards of the clutch by hand..this is how i set my clutch...and it does not lurch when put in gear...and does not slip on power."

What "center nut" is this guy referring to?

  • adam728

Posted February 25, 2013 - 03:39 AM

#5

Just read this:

"I noticed with my bike i can control how grabby the clutch is by adjusting the main or centre nut of the clutch...tighten that nut till you can just barley turn the inards of the clutch by hand..this is how i set my clutch...and it does not lurch when put in gear...and does not slip on power."

What "center nut" is this guy referring to?


Was this quoted from someone talking about a YZ250?


According to the Pro-X cataloge

1993-2013 YZ250
16.2306 friction plates (8 pcs)

1994-2014 YZ250
16.2351 steel plates (7 pcs)

2000 426F
16.2306 friction (9 pcs)
16-2452 steel (8 pcs)

2001-2002 426F
16.2306 friction (8 pcs) plus 1 pc 16.2307 friction
16-2452 steel (8 pcs)


So it looks like you could only use the friction plates, and not the single plate that is different on 01-02 426F.

On the Thumpertalk OEM parts page you can see 1 plate is different. I couldn't tell you why.
Posted Image

  • motoxvet

Posted February 25, 2013 - 06:10 AM

#6

If you're going to disassemble the clutch anyway, you might as well check the steel plates for thickness (mic. them) and check for warpage on a glass plate. I don't think you'll find them warped because that's not your symptom. You can check the fiber plate thickness too so if they are OK, you aren't throwing a new set of plates some other problem. Don't be afraid of clutch work. It's actually pretty easy. If you're VERY careful, you can get the side cover off without tearing a $15 gasket. The MOST COMMON MISTAKE on a rookie doing clutch work is putting the plates back in the wrong order OR with some bikes the plate orientation if they're not a symetrical design. If you install new plates, adjust the cable AND the linkage according to the manual. I hope you have a manual for your bike...

  • Wierac21

Posted February 25, 2013 - 06:43 AM

#7

Thanks for the info guys. I don't have a micrometer but I'll try and borrow one from a buddy. It seems like after reading the interwebs that it is bad springs and fibers like was mentioned above. Adam728 that quote was in in regards to a YZ250 http://forum.dirtrid...tch-problems/p1

I obviously don't want to over-tighten it like he did.

  • Wierac21

Posted February 27, 2013 - 07:20 PM

#8

So I messed with the cable a bit today, and pulled the stator side cover to inspect the push lever axle. I tried wiggling it but it felt very solid and had no play in it. After messing with the cable I took the bike down the street to see if it did anything. Nothing changed. Pulling the lever in still let the bike roll freely in any gear when i had momentum. Also I could put it in any gear and roll on the power and it would pull normal until it got into the power band and then (even in 5th) it would just rev out even though it was not gaining speed.

Could it be something in the tranny or is this definitely a clutch problem only? It shifts through the gears easily without hesitation. When I take off in 2nd or higher I can definitely tell its in a higher gear, its just when I get into any power it slips. Also the clutch sounds pretty noisy to me when its idling. Granted I haven't ever had one of these bikes so I don't know what they sound like.

Its just that the pull on the lever feels better than most bikes Ive ever had. I guess I'll just buy a clutch kit with plates, fibers, and springs and see what that does. I just don't know what else to do at this point.

Edited by Wierac21, February 27, 2013 - 07:23 PM.


  • adam728

Posted February 28, 2013 - 03:10 AM

#9

Thanks for the info guys. I don't have a micrometer but I'll try and borrow one from a buddy. It seems like after reading the interwebs that it is bad springs and fibers like was mentioned above. Adam728 that quote was in in regards to a YZ250 http://forum.dirtrid...tch-problems/p1

I obviously don't want to over-tighten it like he did.

I'd say the poster suggesting that center nut torque can be used to "adjust" the clutch action has no idea what he's talking about, or has a totally different bike with a different setup that might work that way, and assumes it applies to all bikes.

So I messed with the cable a bit today, and pulled the stator side cover to inspect the push lever axle. I tried wiggling it but it felt very solid and had no play in it. After messing with the cable I took the bike down the street to see if it did anything. Nothing changed. Pulling the lever in still let the bike roll freely in any gear when i had momentum. Also I could put it in any gear and roll on the power and it would pull normal until it got into the power band and then (even in 5th) it would just rev out even though it was not gaining speed.

Could it be something in the tranny or is this definitely a clutch problem only? It shifts through the gears easily without hesitation. When I take off in 2nd or higher I can definitely tell its in a higher gear, its just when I get into any power it slips. Also the clutch sounds pretty noisy to me when its idling. Granted I haven't ever had one of these bikes so I don't know what they sound like.

Its just that the pull on the lever feels better than most bikes Ive ever had. I guess I'll just buy a clutch kit with plates, fibers, and springs and see what that does. I just don't know what else to do at this point.


Definitely a clutch problem. Gearboxes don't slip, if they do it's a violent release/engage/pop/bang/clank etc, and typically only occurs in a particular gear (whichever has the damaged teeth/engagement dogs/shift fork).

So the cable has freeplay, but the push lever assembly (#24) is bound tight when the clutch is "released"? (note, this is the YZ250 exploded view, the previous one I posted was to show the 426F extra plate)

Posted Image
  • To start with, I would disconnect the cable and make sure the flat on #23 is exatcly perpendicular to the pushrod, meaning it is in its fully released position, and that the cable hasn't held it rotated and partially disengaging the clutch.
  • I would then make sure #13 is in place, and #14 isn't damaged, as I believe those could cause the hub to seat further on the shaft and leave the clutch gap too large.
  • Also look for any damage to #19, #20, and #23, although they'd have to become longer to push the clutch apart.
  • Make sure the correct number of clutch plates are in there, and they are in the correct order. If a friction plate was left out then the stack height would be much too short and you'd get a ton of slippage even if all the parts were in perfect condition.
  • If all looks good, you could just throw new plates and springs in. Personally I'd measure the spring length and thickness of the plates and see where the problem actually lies. If plates are in perfect shape but the springs are sacked out you can replace them for about $15 from the Thumpertalk store, and not waste money replacing good plates.

The way you describe the clutch noise and also the bound up push lever makes me think there's a damaged component in there causing the issue, not necessarially just worn plates/springs.

  • adam728

Posted February 28, 2013 - 03:15 AM

#10

Wanted to add -
Check out the stickied "faq" thread for a link to download a factory service manual for your bike, they are priceless when it comes to working on your bike.

And, from my 05 service manual (we still don't know the year of your bike)
Clutch spring length : 50.0 mm, service limit 48.0 mm
Friction plate thickness : 2.9 - 3.1 mm, service limit 2.8 mm
Steel plate thickness : 1.5 - 1.7 mm

Edited by adam728, February 28, 2013 - 03:15 AM.


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  • Polar_Bus

Posted February 28, 2013 - 03:40 AM

#11

Sometimes what can happen is the clutch springs can become "laxed" and loose their "free height" . If the previous owner cooked the clutch at some point, this destroys clutch spring performance. Check the springs and see if they are still in spec, or just replace the springs and forget about it..

  • Wierac21

Posted February 28, 2013 - 06:15 AM

#12

Adam728 thanks a lot for a very detailed response. I love forums for the wealth of knowledge that can be had from just a few mouse clicks. I'm gonna go through it all this weekend as I have mid terms tomorrow and I've been studying all week with not much time to mess with my bike. The bike is an 2004. I bought a manual too for pretty cheap offline. I've always preferred to have a hard copy in my hand when it comes to bikes.

Again thanks everybody for the help!

  • Wierac21

Posted February 28, 2013 - 02:50 PM

#13

So I couldnt help but play with the bike a bit today when I got home. I laid the bike over on its side and pulled the case cover off and took a couple pics this time. I found a little watch battery like spacer in part #19 like in the diagram for the 426f clutch. I dont see it in the exploded view for the 250? So I took it out and put it all back together thinking that may have been it. When I did this there was zero clutch lever as in it was just loose and you could pull the lever to the bar with the slightest pull. This kind of freaked me out because prior to that I pulled part #23 all the way out when it was leaned over and I thought it wasnt engaging on the stator side anymore. I tore it back apart and put the battery-type bearing thing back into the cylinder part on #19 and put it all back together. Viola it has tension on the lever again. Also the fibers are only half wet with oil when I pulled them out. I rode it up and down the street the other day for a quick second, which should have lubricated the entire discs. This just seems wrong to me.

I counted the plates and fibers and it has the correct number of each too.

So could this mean the PO has the wrong length #23 in this bike? I didnt have much time to mess with it as Im still studying but I had to play with it a bit today to keep me sane. The basket has some grooves but Ive seen worse. See the pics below, thanks.

Posted Image

Posted Image

Posted Image

Posted Image

Posted Image

Edited by Wierac21, February 28, 2013 - 02:58 PM.


  • Polar_Bus

Posted February 28, 2013 - 03:41 PM

#14

As long as you were able to achieve some amount of "free play" in the clutch lever, missing a linkage spacer will not cause your clutch to slip. Clutch slipping can only be caused by worn or glazed plates, or bad springs/ ie insufficient preload. However if you had no clutch free play, now it's a possibility that something mechanically incorrect was placing a slight amount of disengagement force on the clutch pack causing slipping. The one thing that doesn't look right to me is the fact the last friction disc is sitting so low beneath the inner hub. When I pulled the clutch on my YZ125, the top friction plate was just about flush with the top of the inner hub. I wonder if the top spring pressure plate ( ref pt # 6) is jamming against the inner hub and not allowing sufficient preload on the plates when you tighten down the clutch springs ?

Edited by Polar_Bus, February 28, 2013 - 03:42 PM.


  • adam728

Posted February 28, 2013 - 03:55 PM

#15

That basket is very notched, which won't help matters, and the inner clutch hub is cracked. You can see it in several pics, including the last one (in the 1 o'clock position).

  • Wierac21

Posted February 28, 2013 - 06:15 PM

#16

Holy cow. I didn't even see that. Found one on eBay off a 2001. I'm assuming that would fit mine ('04)? I'm sure it's not good but could that be causing some of my problem?

  • Wierac21

Posted February 28, 2013 - 08:05 PM

#17

I apologize for the bombarding of questions and posts about this topic. I just bought that hub off eBay. I guess I'll just wait till it gets here to pull it all apart for inspection so that when it goes back together I'll have a new inner hub in there.

  • adam728

Posted March 01, 2013 - 01:35 AM

#18

You can check the Thumpertalk OEM parts section and see what the part numbers are for 01 vs 04. I am guessing they are the same.

You are going to need a new basket as well, or at least some careful work with a file. Typically a notched basket holds the fiber plate's tangs in place under load (where the wear has occurred) and makes if very difficult to disengage. However, I have heard of guys having the clutch not engage as the plates wear and the notching won't allow the springs to push the plates together with enough force.

  • Polar_Bus

Posted March 01, 2013 - 02:08 AM

#19

Holy cow. I didn't even see that. Found one on eBay off a 2001. I'm assuming that would fit mine ('04)? I'm sure it's not good but could that be causing some of my problem?


All the pressure plate does is basically bolt to the top of the inner hub. You tighten the spring bolts till the washer under the bolt bottoms out against the inner hubs spring posts. If the inner hub has too much height vs the clutch pack thickness, you wont get sufficient preload because of a mechanical interference issue. Do you have the correct old '04 hub ? Compare p/n's and dimensions. I believe the 4 strokes use one more clutch plate vs. the 2 strokes. This is a guess, but maybe you bought a 4 stroke inner hub ? I've had severall mis represented year id for parts off Ebay, many sellers are salvage yard bubbas that have NO clue about year to year parts id'ing so you never truly know what you are buying so be carefull on Ebay...

  • adam728

Posted March 01, 2013 - 02:56 AM

#20

Polar - I think he means he JUST ordered a 2001 inner hub to replace this cracked hub that has been in the bike since he bought it.

Wierac21 - Meant to say yesterday (but forgot) : THANK YOU. Thank you for taking good pictures to help us help you. I can't count the number of "look at this" threads that have crappy cell phone pics, pics that look like they were taken under muddy water, pics so dark you don't know if you are looking at a spark plug or a flock of migrating geese, etc. The big, clear pics help a ton.





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