YZ 125 clutch issues

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3/3/2019 8:34 PM

I have a 2018 yz125 with about 20 hours. Roasted my clutch first moto today, it was on its way out either way. I installed new fibers and on the last lap of my final moto the lever locked up. Clutch was slipping and cable was adjusted all the way out but I would not pull the lever into the bars. Bike would still move forward but the lever was rock hard.
I run rotella t4 and have on many bikes so I don't believe this is the problem. I abuse the clutch slightly as I am a pretty quick rider but have never roasted one in three motos. Any idea if oil or something may be an issue? I have never encountered a locked up lever from a burnt out clutch and hope it isnt a bigger issue.

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3/3/2019 8:48 PM

Pull it all out check fibers and metals, may be a grooved basket.
I have seen guys rost clutches in 10 min in mud
Dont think its the oil

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3/3/2019 8:52 PM
Edited Date/Time: 3/3/2019 8:52 PM

Thanks for the input
I agree that its not the oil as i have ran rotella for years.

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3/4/2019 10:04 AM

Clutch failure is usually the result of extreme heat, which softens the spring tension and causes slip, which cause more heat and more slip and so on.

The first thing to check is the cable. Disconnect at the lever and you should be able to work the cable in the outer by hand. Look inside the ign cover, check that everything is clear around the actuating arm.

The steel drive plates have to be able to slide along the rails inside the hub. Same with the fingers on the fibers inside the basket. If you have bad grooving of those parts, you might stick the clutch.

Behind the push cap, there is a rod and ball. I can't think of why these parts would have got hung up.
You've got to work your way from the outside in: lever, cable, actuating arm, hub, basket, cap, rod. Hopefully you turn up some damage or interference before you have to go further than the rod and ball.

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

3/4/2019 4:26 PM

Like yzed250 said it's most likely your springs. We run pro circuit spings in all are bikes because like you we are tough on clutches

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3/4/2019 5:17 PM
Edited Date/Time: 3/4/2019 5:20 PM

Yeah stiffer springs are coming with my new clutch pack. YZed 250 thanks for the advice. Turns out the actuating arm had slipped out of its guide boss, and had jammed itself on top of the boss. I had put used fibers in as I didn't have any replacements with me and it was all I could find at the track (Questionable idea in hindsight but didn't want to call it a day after 1/2 moto). Assuming the thickness of these used fibers were less causing the actuating arm to slip out of the boss.

Redduk do you have a yz125? if so what clutch packs do you find best? Will probably go OEM, but I am a college student so riding budget is tight, but cheap internals usually cost more in the long run...

Edit: Appears pro circuit only make springs for the 250 and four stroke yamahas. Any other quality aftermarket springs?

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3/5/2019 3:18 PM

JKMX61 wrote:

Thanks for the input
I agree that its not the oil as i have ran rotella for years.

Do a search on Rotella, A lot of people stopped using it in the last year or so, And Rekluse no longer recommends it.
Lots of info if you search it.

Good luck

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3/6/2019 10:52 AM

JKMX61 wrote:

Yeah stiffer springs are coming with my new clutch pack. YZed 250 thanks for the advice. Turns out the actuating arm had slipped out of its guide boss, and had jammed itself on top of the boss. I had put used fibers in as I didn't have any replacements with me and it was all I could find at the track (Questionable idea in hindsight but didn't want to call it a day after 1/2 moto). Assuming the thickness of these used fibers were less causing the actuating arm to slip out of the boss.

Redduk do you have a yz125? if so what clutch packs do you find best? Will probably go OEM, but I am a college student so riding budget is tight, but cheap internals usually cost more in the long run...

Edit: Appears pro circuit only make springs for the 250 and four stroke yamahas. Any other quality aftermarket springs?

I'd say OEM are good, Hinson or Rekluse probably have some 'upgrade' springs for you, but this is just an idea, and not my personal experience on the YZ125.

You might also look into some clutch hub mods. You might 'port' the OEM hub to get a bit more oil into the pack. There will be threads about this on vital and/or thumpertalk.

Belray and Maxima have excellent dedicated 2-stroke trans oil which is better than the current Rotella formula.

I bought my KTM used at 20 hours and the trans oil was burned pretty badly. I've replaced the oil three or four times and I'm still getting a slight burning smell on the oil. I also need to check that my clutch is not slipping due to sacked out springs.

I usually replace my oil as soon as I have any clutch fade or not longer than 10 hours. My hydro clutch is auto-adjusting, so it's hard to tell, so I usually run 5-10hours. If I boil the coolant, that's another sign that I should swap the oil.

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

3/6/2019 11:27 AM

I was hard on clutches too, we always ran yz250 springs in my 125 and it seemed to help.

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3/8/2019 11:19 AM

Looked into the hub mods, dont plan on going that route unless I keep burning through plates in <8-10 hours. Ended up with a tusk kit cause it was only 50CAD. I have had good luck with their products before and see decent reviews for the clutch packs. If it only lasts half as long it is still worth it imo, and came with stiffer springs, might run 250 or 250f springs if these dont cut it. Took a caliper to the friction discs and they are well within spec, and look pretty decent, will update on the tusk plates as they are a screaming deal if they are decent.

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