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YZ125 Clutch Question

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Dec 10, 2006
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#1
Hi all. I am considering the purchase of a YZ125 from a coworker of mine. He brought it out for me to test drive one afternoon, but our test drive was cut short because the clutch seemed to fail--engine ran and revved up just fine, but the bike would not go anywhere--severe slippage.

Part of our deal is pending on whether we can get the clutch fixed ourselves. Not knowing anything about brand or which parts to buy, I went and picked up a clutch and spring set off of ****:

Edit: Can't post names of sites. I bought the clutch from a large online auction site for 49.99.

After doing some searching, I'm wondering if I bought the wrong brand or if I made a wrong move. I'm not looking for anything special or fancy. I want this bike to scoot me around a trail or two and not breakdown while doing that :).

Thanks,
Ryan
 
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#2
Did you buy a complete clutch or just the clutch plates??? Normally, when they start to slip (high speed at first, quickly followed by total lack of use of the clutch), you just need to replace the fiber plates. Springs are a bonus, but occassionally do need replacing. If you bought the clutch plate set, drain the oil, take off the clutch cover, remove the bolts over the springs, take out the old plates PAY ATTENTION TO WHAT ORDER THEY ARE IN. Some bikes use only one size fiber plate, some use one or two thicker in places. Coat or soak the new plates in oil (motor oil you are going to use for transmission). Put back together just like you removed everything.
If the clutch plates fit snugly, they should work. If they don't fit snugly, they may be the wrong plates. As far as brand goes, hard to say since you didn't tell us what brand you received.
If you bought used parts, you might have the same problem you started with.
 
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#3
I'm sure it will work out fine. Use the manual you have and get it done. I want to be out on the trails on the 22nd.

Chris
 
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#4
what exactly is clutch slippage? its been explained to me many times but i can never get the concept.
 
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Mar 30, 2006
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#5
What the clutch does is engage and disengage the transmission. It does this by pushing the clutch plates apart and and when you release the lever the springs pull the plates back together. If the plates are worn out they are not putting enough pressure on themselves to fully stick. When a load is put on the motor the plates should not slip. When they wear out thats what they do, they slip. This causes your motor to rev up but you not going anywhere. When you first put the bike in gear and take off you slowly let out the clutch and give it gas. The bike is revving up but your moving slowly to get going because the plates arent fully together and once the clutch is fully disengaged you have normal power. But if you hold the clutch lever halfway out you can rev the bike all you want and not go very far very fast. This is slipping the clutch.
 
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#6
2strokerfun said:
Did you buy a complete clutch or just the clutch plates??? Normally, when they start to slip (high speed at first, quickly followed by total lack of use of the clutch), you just need to replace the fiber plates. Springs are a bonus, but occassionally do need replacing. If you bought the clutch plate set, drain the oil, take off the clutch cover, remove the bolts over the springs, take out the old plates PAY ATTENTION TO WHAT ORDER THEY ARE IN. Some bikes use only one size fiber plate, some use one or two thicker in places. Coat or soak the new plates in oil (motor oil you are going to use for transmission). Put back together just like you removed everything.
If the clutch plates fit snugly, they should work. If they don't fit snugly, they may be the wrong plates. As far as brand goes, hard to say since you didn't tell us what brand you received.
If you bought used parts, you might have the same problem you started with.
The kit I bought included new springs, clutch plates, and friction discs.

Can anyone recommend what oil to use and where to buy it? 2 stroke motor oil? 2 stroke transmission oil? Mobile One synthetic like I use in my car?

After I ended the auction, I realized that there was no brand specified on the auction. That was a little stupid on my part, but the seller has many transactions with good feedback :think:.

Chrisbuoi: Me too! :aj:

TIA,
Ryan
 
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#7
I'm sure they will be fine. A lot of times those plates on F-Bay are made by Vesrah, which I like just fine. As far as oil, I like 20w-50, but others prefer something a bit thinner and some people prefer ATF. You will need a manual, which probably has the best recommendation. Any regular good motor oil should suffice until you get a manual or a recommendation from someone more familiar with the YZ than I am.
 
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Dec 10, 2006
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#9
Thanks for the help, 2strokerfun.

Chrisbuoi:

I checked the (Clymer) manual I have and it specifies:

a. Yamaha Lube 4 (10W-40)
b. SAE 10W30
c. SAE 10W40

I've got tons of dino oil in assorted flavors. Hopefully, this clutch swap will do the trick. I'm excited about owning my first dirtbike.

Ryan
 
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#11
rmc_olderthandirt said:
Did you check to make sure that the clutch cable wasn't adjusted too tight?

Rod
I have not checked that. However, we had been riding the bike for 15minutes without a problem. Over a 3-4minutes period it went from not going very fast to not going hardly anywhere. It would barely move in first gear.

Ryan
 
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#12
Follow up post:

Swapped in the new clutch and the bike is running great. Rode for about 4 hours yesterday and everything is working just fine. Total cost was $56 for the clutch, $2 for 1 qt of oil (I used Castrol 10W30 motor oil) for the trans fluid and it took me about 30 minutes to install.

Ryan
 
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#13
rmc_olderthandirt said:
Did you check to make sure that the clutch cable wasn't adjusted too tight?

Rod
Yeah you need a little bit of slack to make it work just how you want it.
 
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#14
Followup: I seemed to have been noticing some engagement (disengagement, rather) issue lately. After closer inspection, I've noted that the clutch basket has started to show some definite sign of wear (grooving). Looks like I am in for a new basket.


Ryan