Clutch worn out or....?

Hi chums,
The clutch on my R has started slipping under load. I suspect the plates are worn out as the biting point is very near the end of the lever travel. My question is could this slipping be due to any problem in the hydraulics or either of the cylinders?

Hi andy, my clutch also slips under load and has a newish ebc heavy duty fibre set fitted. I was going to fit new steels but i only started to get this problem when i changed the master cylinder for a radial one and changed the fluid and clutch hose so it maybe the master on mine. When i built the bike the clutch fluid looked like mud and was probably the original oil so i replaced with dot 5 thinking that it would be better but within a year it too looked like muddy water that is why i replaced the master and hose. I would recommend checking the return hole in master cylinder reservoir isnt blocked first then next time you do an oil change check the plates, the fibre plates in mine had disintegrated and there was bits of plate in the sump so it was obvious what was needed but the steels are a bit harder to check though i should have replaced them at the same time.

Ps. Tyres finally arrived yesterday! Dunlop came up with some poor excuses for the delay, hope you got yours ok.


Cheers Gaz, I’ll check the return hole and change the fluid this weekend. Front tyre arrived 2 weeks ago and I got it fitted yesterday at National Tyres for £10, not been out to try it yet. I hope it cures the 40mph hands free death wobble!

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Dunlop claimed that my tyre was stolen before they could deliver it to tyre tech then they claimed there was a problem with tyre tech payments, bloke from tyre tech was great he rang me up about 4 times apologising for them and was more upset by the entire process more than i was.


Yes, he always keeps me updated by email, problems seem to be at dunlops supply side.

Id start by pulling the slave cylinder as the piston can seize/bore corrode which affects its movement. Simple to do, and you can polish up the piston, clean the bore and check the seal etc. Dot 4 refill and see how you get on. Then next step if thats not sorted it pull the clutch cover and check the plates and the clutch spring. You might find its not the plates but the spring out of tolerance.


Hi Viffer,
I`ve had the same prob on my RF. I changed the clutch spring, the friction plates and the metal ones. But that didn´t help at all!
In the end it was the simple oil change from the a partly synthetic oil to a standard mineral oil that showed improvement. I would try that first, if you should use synthetic oil at the moment.
Best wishes

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Cheers JK, I bought this bike earlier this year so I don’t know the engine oil situation. So far I have only flushed and replaced the manky clutch fluid, which made no difference to the biting point as expected. So I will strip and inspect/measure the clutch components in the next few weeks, and replace engine oil with dinosaur derived 10/40 and take it from there.

Not just a matter of using old fashioned oil. It has to be formulated for 4 stroke motorcycles to be sure. Most oils formulated for cars etc. have additives for friction reduction and lots of other things. As most 4 stroke motorcycles have wet clutches, they don’t handle the anti-friction additives very well and it tends to make the clutches slip. The only way to be sure is use oil specifically designed for use in 4 stroke motorcycles or other oils that definitely have no anti friction additives. Cleaning and inspecting the plates etc. will certainly help.
An old trick that I used for flushing out and cleaning old brake and clutch lines was using methylated spirits to flush out the whole system after draining them. It does not hurt the lines or seals for dot3 fluid but can’t guarantee it for dot4 and above as have not had to use it on any dot4 or higher systems. Maybe another member has?

Thought I would do some research on brake/clutch fluid. Apparently up to Dot 4 and 5.1(which has no relation to Dot 5) are all compatible and Metho will clean out the system with no problems. Dot 5 however is made of silicon and not compatible with any of the others and I would not use Metho to clean out these systems. Obviously, some of you would know this but some may not. The larger the number the higher the boiling point and the less likely to absorb water, which causes problems like spongy brakes/clutches when it boils and vaporises. Unfortunately, it also causes the cost to rise as well.

Oh yes I only ever use Motorcycle oil!