yz125 , clutch is driving me crazy (dragging)


Dr Rockso

Member
Oct 15, 2007
43
0
i got this 88/89 hybrid yz125 and i can't get the clutch to stop dragging . it's an 88 frame with an 89 engine in it . i've tried just about everything , heres what i know as of now .

all my plates are good and sit flat on a piece of glass

the basket isn't grooved up but it's an 88 basket , the 88 used a different style clutch , but the basket is supposed to be the same . everywhere that sells replacement baskets lists that their one basket fits 88-91 yz125 , so i guess it doesn't matter that it's an 88 basket .

the 88 and 89 clutch cables are different , but i have both and neither make it stop dragging .

i had a spare clutch cover that was busted so i cut a window in it and put it on the bike , the pressure plate is disengaging just fine with what looks like more than enough room to seperate the plates (this is the style of clutch with 2 smaller friction plates and a spring plate to help seperate them)

no matter what i do when i put it in gear it stalls out . i've adjusted cables , rebuilt the clutch pack about 20 times , the basket and hub aren't all grooved up . i'm really running out of ideas . only other thing i can think of is oil , i'm using the same atf that my friend uses in all his bikes , maybe mine doesn't like atf for some reason . anyone have any ideas ? all this bike needs to be perfect is a working clutch , then i can finally go riding .
 

BLACKeR

Member
Oct 30, 2007
76
0
is your pressure plate or your inner hub worn at all on the face that pushes against the clutch plates? i dont know if im describing this properly, but ive had on old engines the faces of the pressure plate and inner hub wear enough that they could no longer work properly.
 

BSWIFT

Sponsoring Member
N. Texas SP
LIFETIME SPONSOR
Nov 25, 1999
7,926
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the clutch pack about 20 times , the basket and hub aren't all grooved up
Do the "tangs" on the fiber plates move freely through the fingers of the basket?
Do the "teeth" of the metal plates move freely on the spline of the drive gear?
By rebuilt, do you mean you have replaced the metal and fiber plates?
Have you tried new springs?
With the clutch lever pulled in, what is the largest feeler guage you can put inbetween the plates?
The discription of your problem leads me to think your basket is notched but you have stated that it is not. Does the pressure plate slip on and off the drive sproket easily?
The next thing to look at is the operating mechanism. Check all of the moving parts between the cable hook up and the basket. Typically, the cable makes a rotational motion into a lateral motion. If the connection is cracked, you will not get enough throw in the lateral direction.
The other thought that I have is that your clutch pack is too thick. Insure that all of the plates are within spec.
 

holeshot

Crazy Russian
LIFETIME SPONSOR
Jan 25, 2000
1,823
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Dr Rockso said:
i. i've adjusted cables , rebuilt the clutch pack about 20 times .


What do you mean by that? You've actually put in 20 new sets of fibers and metal plates? (not at the same time, of course). Some aftermarket clutch sets are slighly thicker than stock and can cause clutch drag (I always use OEM to avoid this).

Also, most times when I change to new fibers, the clutch drags for the first few minutes or so of riding (until the excess oil between the plates is squeezed out). This only happens if you soak the plates before installing.

Just some throwing some thoughts out there ...
 

Dr Rockso

Member
Oct 15, 2007
43
0
i mean i've had the clutch completely apart and back together 20 times . all the plates are oem replacements . they're in the right order , yet still when i click into gear it stalls almost immediately . the center hub wasn't grooved but was slightly wavy i've run way worse ones a million times before without problems but i guess this one just likes to be a pain . i'll try filing down the waves and see if that does it , but they're seriously tiny . the bearing for the basket is good , so i can rule that out . the pressure plate is smooth where it touches the outer friction disk so thats not it . i'm really starting to hate this bike
 

Dr Rockso

Member
Oct 15, 2007
43
0
BSWIFT said:
Do the "tangs" on the fiber plates move freely through the fingers of the basket?
Do the "teeth" of the metal plates move freely on the spline of the drive gear?
By rebuilt, do you mean you have replaced the metal and fiber plates?
Have you tried new springs?
With the clutch lever pulled in, what is the largest feeler guage you can put inbetween the plates?
The discription of your problem leads me to think your basket is notched but you have stated that it is not. Does the pressure plate slip on and off the drive sproket easily?
The next thing to look at is the operating mechanism. Check all of the moving parts between the cable hook up and the basket. Typically, the cable makes a rotational motion into a lateral motion. If the connection is cracked, you will not get enough throw in the lateral direction.
The other thought that I have is that your clutch pack is too thick. Insure that all of the plates are within spec.


this style clutch uses the splined stump sticking thru the pressure plate , the outer cover has the actuator on it which pulls the stump and in turn disengages the clutch . the spare clutch cover i had i cut a slit into so i could watch the clutch move , otherwise you can only use the clutch without watching it . theres really no way for me to put a feeler guage in there , but it looked to me like it was opening atleast an 1/8 of an inch if not more . but i've tried it with all the slack taken out of the cable before , to the point that when you're not even touching the clutch it's already pulled a tiny bit , and even that wouldn't let the clutch disengage .
 

Dr Rockso

Member
Oct 15, 2007
43
0
ok , well just for the hell of it i went back to the bike and put the cover with the window back on and started messing with the clutch , the pressure plate moves more than enough and the plates move freely with the clutch in , it just still draggs like hell , and i can only assume at this point thats it's something personal between the bike and me and it's doing it just to piss me off because there is literally nothing that it could be . i'm so getting ready to sell this stupid bike .
 

awhtx

Member
Oct 10, 2007
18
0
I have a 1989 YZ125 and I know for a fact that the factory part number for the clutch basket is NOT the same for '88 and '89. '89 and '90 use the same clutch parts but they do not have the same factory part numbers as the '88 or '91. Since you have an '89 engine I'd put all of the '89 clutch parts back in and see what happens. Also, the second or third fiber is smaller than the others and there is a special steel spring that goes in the stack with it. I don't know what it's purpose is but have you installed it?
 

Dr Rockso

Member
Oct 15, 2007
43
0
the part numbers are only different in the first 3 digits and they're just to show year , all the aftermarket clutch basket makers list one basket fitting 88-90 or 91 i forget . either way that bike pissed me off for the last time , i traded it to some guy for a honda odyssey 250 , should be fun in the snow . anyways thanks for your help guys , but it's dudes problem now :laugh:
 

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