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clutch slipping

Old 05-15-2013, 02:00 PM
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clutch slipping

My clutch some times slips under hard acceleration. if I rev it high in any gear and shift and get back on the gas once I've shifted the revs hang and then come down after a 1/2 a second to a second. Some times it doesn't do this.

I am running rotella T6 15w40 oil. My clutch fluid also hasn't been changed in what looks like to be forever. It looks black. I plan on doing this as soon as possible but I'm not entirely sure how to bleed it.

Also I find it hard to launch my bike. If I try it usually ends up just acting like I dumped the clutch even when I clearly didn't. I can't seem to give it a decent amount of gas without the clutch just dumping itself.

Could it just be my clutch fluid?
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Old 05-15-2013, 02:12 PM
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Start with the clutch fluid for sure. It's the easy fix and has a high probability rate for causing your issues. Seems like you already know this .
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Old 05-15-2013, 02:16 PM
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You might try changing the oil to a m/c semi-synthetic...
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Old 05-15-2013, 02:21 PM
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In a nutshell, here's how I personally do this:

1) Acquire Dot 4 or compatable brake fluid. New bottles are better b/c they haven't been exposed to humidity in the air (water is bad for the stuff)
2) Hose to fit on bleeder and wrench... I think it's 8mm
3) Open fluid reservoir. If it's extremely sludgy (esp at the bottom) you may want to skip bleeding and do a full rebuild on the M/C. If the fluid is just gross, you may get away with continuing the flush.
4) Fill reservoir all the way to the top. Put hose and wrench on bleeder valve.
5)Squeeze clutch lever and then slowly open bleeder valve. The clutch lever will become light and fluid will come out of the bleeder. Close valve before the fluid has time to "return"
6) Release clutch lever fully and then repeat step 5 several times until the fluid is clear.
7) After flushing, pump the clutch lever several times and watch for bubbles coming out of the reservoir. Sometimes bubbles get stuck in the system and are known to cause the issues that you're experiencing. Sometimes I'll go from step 5 to 7 a couple of times to make sure everything's flushed and no bubbles are left. It sounds tedious but it really takes less than 10 minutes for this part.
8) Fill up to the fill line and wipe of all of the DOT fluid as it is not particularly good for paint.

I think that covers it. Hopefully it just needs a good flush (and not a rebuild). If that doesn't work then switch to motorcycle oil.
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Old 05-15-2013, 02:21 PM
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Originally Posted by Wicky View Post
You might try changing the oil to a m/c semi-synthetic...
Rotella T6 meets the certification requirements for JASO-MA
In Other Words.. it IS A MOTORCYCLE OIL
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Old 05-15-2013, 07:26 PM
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I had a similar problem and it turned out that the clutch was always under pressure.. I filed down the push pin on the leavers, the clutch engages about 1/2 way out now not in the final 1/8" and it dosn't slip anymore..
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Old 10-30-2018, 01:35 AM
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Originally Posted by Caffeine View Post
I had a similar problem and it turned out that the clutch was always under pressure.. I filed down the push pin on the leavers, the clutch engages about 1/2 way out now not in the final 1/8" and it dosn't slip anymore..
It's kind of weird...along with the slipping, I have to pull the clutch RIGHT in to disengage it. I let it out a few mm and it engages. Boom straight away. No play.

Originally Posted by Wicky View Post
You might try changing the oil to a m/c semi-synthetic...
I was thinking that too but seems my oil should be ok...it is deemed a motorcycle oil and others use fully synthetic.

I am starting to think, I need to rebuild my master and slave cylinders....especially considering my clutch engages almost instantly when releasing.

Might need to re-check the torques on my spring bolts....
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Old 10-30-2018, 05:01 AM
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Originally Posted by executioner View Post
It's kind of weird...along with the slipping, I have to pull the clutch RIGHT in to disengage it. I let it out a few mm and it engages. Boom straight away. No play.



I was thinking that too but seems my oil should be ok...it is deemed a motorcycle oil and others use fully synthetic.

I am starting to think, I need to rebuild my master and slave cylinders....especially considering my clutch engages almost instantly when releasing.
Might need to re-check the torques on my spring bolts....
Do some research and tell me what kind of anti-sheer additives that diesel truck oil has in it for motorcycle use, please and thank you. It was/is not made for use in an engine where it is exposed to transmission gears.

I think your your next step should be to buy rebuild parts for your master cyl and slave. They will not cost you much at all and I guarantee the system needs it.
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Old 10-30-2018, 10:55 PM
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The oil is a "motorbike oil" so should be all good in that department.

Rebuild kits for master and slave are on their way...should arrive in a couple days hopefully.
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Old 11-05-2018, 03:15 PM
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Originally Posted by Wolverine View Post

Do some research and tell me what kind of anti-sheer additives that diesel truck oil has in it for motorcycle use, please and thank you. It was/is not made for use in an engine where it is exposed to transmission gears.

I think your your next step should be to buy rebuild parts for your master cyl and slave. They will not cost you much at all and I guarantee the system needs it.
While I can't give you any research regarding anti-shear, etc. I will tell you that I have used Rotella-T in all of my street bikes, and all of my race bikes for many years. No related failures. Ducati rep even "kinda" referred to it as the USA Shell Agip for us Ducati racers...dry and wet clutches a several years back.

Of course I know that every time an oil thread is introduced on the internet a kitten is killed. Sorry...
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Old 11-06-2018, 05:57 AM
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If you are filing down your lever then really you should bleed it properly. The lever is just the actuator, not the problem. Air is the problem.

I put a banjo bleeder nipple at the top banjo bolt where the air actually rises to. Makes the process much easier. I did have to rebuild the slave cylinder due to awful gunk and sludge. These bikes almost always need that.

Its a self perpetuating problem. Air in the system causes sponginess and it fights against the clutch springs which causes slippage (even when you don't notice it) and premature clutch wear which causes more slippage etc.

Its a pain but you have to rebuild the slave usally and spend quality time bleeding the system.

You can yank the clutch to inspect it w/o draining the oil if you tip the bike. If you still have friction material on the plates you probably still have some miles left if you bleed it. But yeah change the fluid at least. Cheap insurance and will always help anyway.
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