Yamaha YBR 125 - Instant stall after replacing clutch plates

Anthonyyb · L Plate Warrior Joined: 19 May 2021 Karma :

Hi, I was getting a lot of slip on my YBR 125 so I had a look at my oil and clutch plates. They were pretty bad and the oil didn't look like it had been changed in ages... I only recently bought the bike.

I ordered the new plates and they are an identical fit. Removed the casing, the clutch basket, popped in the new plate, then metal plate, and so on (4 plates + 3 metal plates between each). Tightened the basket back down with the 4 springs until they were snug. Put the casing back on, starter motor and kick-start.

Just put new oil in. When I start in neutral all sounds fine, as soon as I shift into first with the clutch lever fully in it stalls quite badly and I go flying forward.

I didn't play with the clutch cable or adjustment, do you think it could be this? Or maybe I've tightened the basket too much which means it won't release even when the lever is pulled?

Any thoughts on what to check would be appreciated. I'd prefer to try things outside of the casing first as I don't want to waste the oil I just put in by opening it up again Sad

Thanks
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Yamaha YBR 125 2010

Easy-X · Super Spammer Joined: 08 Mar 2019 Karma :

Did you soak the plates in oil before fitting or just lob 'em in dry? People have various opinions on this point...

It sounds like the clutch isn't disengaging when you pull the lever. Quick test you might try without the engine running is to lob it in gear and try rocking the bike back and forth. Obviously the back wheel will lock up but if you pull the level does anything happen - slightly less resistance?

If the lever does nothing effectively you'll probably have to take the clutch apart again and see if there's something you've missed.
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Husqvarna Vitpilen 401, Yamaha XSR700, ~~Honda Rebel,~~ ~~Yamaha DT175,~~ ~~Suzuki SV650 (loan)~~ ~~Fazer 600,~~ ~~Keeway Superlight 125,~~ ~~50cc turd scooter~~

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

jeffyjeff · World Chat Champion Joined: 02 May 2020 Karma :

In all probability, the oil looked so bad because it had a lot of burnt clutch plate material floating around in it. It's a good thing you changed it. As for your clutch, here are a few thoughts:

It is not likely that overtightened pressure plate bolts are preventing the clutch from releasing if the other parts are correct; the bolts bear against the springs, not the pressure plate directly.

Did you replace the metal plates as well as the friction plates? Old metal plates could be warped from heat, affecting the thickness of the clutch pack. Discoloration is a sign of overheat.

Are the springs correct? The previous owner might have swapped the clutch springs in a misguided attempt to correct a slipping clutch. Wrong springs can bind on assembly, preventing the fresh clutch pack from releasing (unlikely, but possible). Likewise, the clutch could have bound up on assembly if you were inattentive, or did not tighten the assembly evenly as it went together.

Also, problems with the push lever assembly, bellcrank, or push rod might not be allowing proper action of the push rod against the pressure plate.
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History shows again and again how nature points out the folly of men - BOC

Anthonyyb · L Plate Warrior Joined: 19 May 2021 Karma :

Thanks for all the replies, you responded a lot sooner than I thought anyone would!

bikenut · World Chat Champion Joined: 21 Nov 2011 Karma :

You have a manual, but check on CMSNL exploded views just to be sure.

Someone has been in there before you and taken the clutch off at least....that nut locking tab was not bent like that in the factory. It's there to stop the clutch nut from coming off, is the nut tight, and any existence to say the engine has been apart further....you got a new clutch cover gasket, yes ?
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nuts about bikes

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Leave the tab washer along it's doing it's job now. If you have to work on it again order a new one.

BTW the pushrod gap does not open up as the plates wear it gets smaller until the pushrod is eventually touching the release bearing all the time and that's what makes your clutch slip.

So many people fail to grasp the fundamentals of adjusting cable clutches. I've posted it here many times but once more won't hurt.

There are usually two things to adjust on a cable clutch - the pushrod clearance and the cable free-play (some cable clutch bikes don't have a pushrod and those mostly only have cable adjustment). Sometimes adjusting the cable free-play can have the effect of adjusting the clearance but it's not the proper way to do it.

First you loosen the cable adjusters. Usually this means screwing in the threaded adjuster at either the engine end or the lever end so that there's a lot of slack in the lever.

Next you adjust the pushrod clearance. This varies from bike to bike - on your bike it's the adjuster under the clutch cover, on other bikes it can be the other end (a Bandit for instance has the screw and locknut under a rubber grommet in the sprocket cover). Once you have adjusted the pushrod you then go and set the cable free-play by winding the cable adjuster back out until you are happy with the lever action. You MUST have some free play and it gets less when you turn the bars full lock so check that you're not losing all your slack when you turn full lock both ways.

After that you just make sure the locknuts are tight and you're all set.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy

jeffyjeff · World Chat Champion Joined: 02 May 2020 Karma :

Place the steel plates on a flat surface and inspect for warpage. A piece of plate glass and a feeler gauge are standard tools to use in gauging the amount of warpage.

Clutch cable adjustment: you want some free play at the lever. Insufficient free play and the clutch slips. Too much free play and the clutch won't fully disengage. The amount of free play that could cause your problem would be obvious. The lever would move some distance through it's arc before you feel the cable take up slack. You should feel some resistance when you pull the clutch lever, and the lever should return outward under spring force (from the clutch springs). If that's not happening, something is wrong.
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History shows again and again how nature points out the folly of men - BOC

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Brand new clutch. Why would the plates be warped?
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy

jeffyjeff · World Chat Champion Joined: 02 May 2020 Karma :

Anthonyyb · L Plate Warrior Joined: 19 May 2021 Karma :

Hi all - I managed to get a chance to look at it again Saturday morning and I'm happy to say that it is now fixed!

I followed your instructions Pete (along with looking around to see YBR specific videos and advice).

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Well done. Not being able to select neutral from 1st is a common fault. You might be able to improve it a bit by re-adjusting the pushrod for less clearance or even reducing the cable free-play, but it could equally be a sign of warped steel plates or it might even be the wrong grade of oil. My guess is that it will repidly improve.

You could get into the habit of snicking it into neutral from second as you approach a stop. You shouldn't need to find neutral from first that often anyway.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy