Clutch slipping around 7-8k revs

Howdy folks

I have noticed when I open the throttle the clutch slips around 7-8k revs and regains 'traction' after I ease off the throttle. (By slip I mean the revs quickly jump up to the red limiter and continue to do so if i shift up around that rev range)

Backstory: This has only happened since I took it for a service (3 months ago). The mechanic changed both the clutch fluid and brake fluid which he said 'hadn't been changed in 10 years'. I am not sure if he did anything else involving the clutch.

Living in a city I rarely have the chance to fully open up but having taken it out recently I can verify this slippage happens almost every time.

Any ideas on what might be causing this and if there is an easy fix? And if each 'slip' is bad for the bike?


Thanks in advance!

 

Sounds like the clutch springs and/or friction plates are wearing out. Just replace both.

 

Plan on replacing friction plates soon. :cower: It will only get worse.

As with most bike problems, it helps alot to state the mileage. :disturbed:

 

Millage is 71000

Is it easy to replace friction plates, would I be able to do it myself (beginner)

Why would this slippage be happening after a clutch fluid change?

 

Its happened after a lot of things, why do you assume there is a connnection? Yes its easy to do, you just need a clutch cover gasket .

 

I don't believe fluid change had anything to do with slippage, just a coincidence. Unless you're the original owner we'd never know if the clutch had been replaced previously, but it's unusual for a clutch to last as long as 71K.

Yes, you should be able to do the work yourself after you read, study, and understand the service manual and have proper tools.

Main danger would be over-tightening clutch spring bolts or case cover bolts, easy for a novice to F-up.

 

Ok thanks guys. I will look into it.

Out of curiosity, why would the slippage be happening so late in the rev range and not though all of the revs?

 

Cuz you're in the range of maximum torque and load on the clutch is why. Aerodynamic drag plays a part too.

 

year make model etc???
I am at 70,000 miles on my original clutch plates and its fine, no slipping. I wonder if the mechanic changed your oil with automotive oil that isn't compatible with wet clutches?
Either way, a tear down and inspection is needed. Its a pretty simple job, just remember to lay all the plates, springs and various components out in order so you know exactly how everything goes back together.
Also, make sure everything is lined up perfectly before you torque it down and torque down to specs.

 

Yeah, the oil could be the culprit, but, it could also be the clutch itself getting old. I suppose an oil change could be done again while making sure it's motorcycle specific oil. Rotella T6 is good and inexpensive. If nothing else, it would save you money.

 

10 years ago when I got my first motorcycle I put royal purple synthetic automotive oil in the bike because I didn't know any better. It slipped a lot and never came back even after two oil changes. I eventually installed a barnett clutch that was way too grabby and sold the bike. Never made those two mistakes again lol.

 

The bike is a 1994 vfr with 71000 miles on it. I bought it at 68000 with no clutch problems and with no history of any clutch changes.

The oil was changed at its service (along with various fluids) with 'unbranded' semi-synthetic oil. It was already on semi-synthetic before its service and I will change the oil this weekend (2000 miles later) to a Motul branded semi-synthetic.

At some point in the spring I will probably delve deep into the plates but as for now this 8k slippage is a rare occurrence for city riding ... Unless of course this is a bad idea and should be replaced immediately?
I learnt the hard-way when postponing fixing the fateful charging problems, could this slippage leave me stranded or ruin the bike in any other way?

 

Unbranded semi synthetic sounds suspect. I would not commute on the bike until the issue is resolved.

Sent from my A0001 using Tapatalk

 

I assumed you took it to bike shop for service by a bike mechanic. What you're describing is exactly what would happen if your new oil was a car type oil that had an "Energy Conserving" marking (like a round seal). Those have friction modifiers in them that reduce friction - especially in motorcycle wet clutches. Do you know for sure what oil he put in? If it was a Ducati or BMW shop (dry clutches) he might not have realized what he was putting in. Sometimes a couple of short cycle oil and filter changes with good old fashioned dino motorcycle oil or, my favourite, Shell Rotella 15W-40 T5 diesel oil will clean things up and stop the slipping. Maybe put some Seafoam in the second oil change. I would do this (and have) before taking it apart.

Cheers,
Glenn

 

I bet it was the oil. I have heard of it happening before on CBR's with a fair amount of wear on the clutch. I know a guy with a F4i that has 200k on it with an original clutch......... working fine.

 

I did take it to a bike mechanic who services a wide range of makes & models. He had two large messy, plain containers, debating whether to use fully synthetic or semi, opting for semi saying ''there would be no difference with the amount of miles your bike has done - semi is cheaper''. I assumed he uses the same oil on most bikes that go in for servicing as there was no evidence of different oil types apart from fully or semi.
It does seem abit dodgy looking back on it although I wouldn't have known better at the time.

All in all I will change the oil tomorrow and ride out some millage, It makes sense it will probably need a few shorter cycle changes to remove the old stuff. If the problem persists I will open up the plates.

 

Before you dive into the clutch, drain and replace the clutch fluid again, making sure the slave cylinder is emptied completely. Old, dirty fluid can cause slippage problems as well. Easy job and you can have confidence that it was done right.

 

Thread from the dead.


I am having clutch slipping problems similar to the OP on the 99 I bought with 67K miles on it. I've already got the clutch disks soaking in oil but this caught my eye as the clutch fluid is nasty! I guess I'll get to flushing it when I replace the clutch disks and springs along with the engine oil as well. I figure this will handle all possible causes at once. Hopefully the grabbing at the end of the clutch engagement too.

 

To be honest still haven't even checked, just been living with the slippage. I have bought all the necessary fluids for a change when I have time before summer.
I have however noticed that the slippage only happens on certain gears, most noticeably 3 and 4 which could hint at worn out clutch disks (some more worn than others)? - correct me if i'm wrong.

Anyway after I check and change fluids I will have a clearer idea on how to proceed. I have changed the oil since then which hasn't solved the problem.

 

I got the clutch replaced and I have cleaned out the clutch reservoir. There was literally mud in it. °.°

I'll most likely take the slave apart and make sure there isn't mud in that too, then bleed it. It's no longer slipping though, so that's good.