I'm having some slight clutch slip from approx 7000 rpm upwards on my 1993 1KF. I haven't had the bike long, and haven't really had an opportunity to give the bike a good twist of the wrist until recently and it seems to slip at higher revs.

It doesn't seem like it's slipping to badly at the moment but it's definitely noticable, and i know it will get worse over time / mileage. I have bled the clutch through with fresh fluid today even though the clutch action as seemed fine since i have had the bike, the old fluid was fairly nasty with grey gunge right at the bottom of the resevouir - that hasn't made any difference (not that i thought it would, but glad i've done it anyway)

After doing some general reading up it seems like it could either be the friction plates on the way out, or the steel plates "blued", warped or too smooth to grip properly. or even the springs may need replacing. The bike is due an oil change soon, and i have no idea what oil the previous owner might have used, or how many miles the bike have covered since the last oil change (but i plan to do it asap).

Has anyone experienced clutch issues like this before and what would be the best course of action to sort it? From the symptons i describe what would be most likely to be causing the slippage? I was thinking of ordering new friction plates and fitting them when i change the oil and filter but if it's worn springs or steel plates i guess i will need to have the clutch cover off to do a visual unspection to see what could be the cause?

 

An oil change will not likely fix the slippage. If serviced with the wrong oil,( lo viscosity/friction modifiers) the friction plates will absorb the slicky stuff and likely will not flush out with the oil change.
If the friction plates are worn, and have been for some time, the steel plates may have some heat damage. Not knowing the maintenance history, prepare for the worst (friction/steel/springs)and hope to be presently surprised. IMO, if I open it up, it gets friction plates and springs anyway.

 

Thats the trouble - not knowing the service history, i know the oil needs replacing and every time i buy a used bike then as a matter of course the first thing i do is change the oil and filter. I've never had to replace a clutch on a bike before, but i do know how to do it - it's just knowing whether to open the clutch up and inspect it would be the best thing to do before changing the oil. When i inspect the clutch components, what tell-tale signs should i be looking for that could be the cause of the slipping?

From what i have been reading on general clutch slippage on the web, some people suggest roughing up the steel plates slightly with wet/dry - is this a good idea???? or just masking the problem...........

If i have to end up replacing the clutch, what replacements would folk recommend? I've been looking at ebc heavy duty at around £50 just for friction plates.

 

I don't have experience with anything outside of Honda factory friction plates, EBC and Barrnet have good reputations. The steel plates will be fine as long as they are not warped from overheating. Some slight discoloring is ok. The surface is dimpled and I suppose you could duplicate the pattern with a light auto-centerpunch action???

 

Complete EBC srk kit has dimpled friction plates

avail UK Ebay

FWIW if there was reg motor oil put in it by the PO
then I'd run diesel oil in it for an oil change putting
at least a 1 k miles on it before changing. The high
detergent compounds in diesel oils can help deglaze
clutches that have be subjected to automotive oil
with friction modifiers in it known over here stateside
as "energy conserving" motor oils. Probably gets some
kind of green tree hugging stamp across the pond.

My 1990 had this issue when I first had it, diesel oil
did the job for me back then.

 

If it's slipping at 7000 - that's pretty much where the power comes in. Replace the friction plates - the steel plates generally don't need replacing unless they are warped.
I'd replace the clutch springs if the bike has high mileage - I agree with Sprock on the diesel oil - it's all I have run in my bike for the last 80000 k's. Perfect bike oil at a quarter of the price !

It's an easy job, no more than two hours to complete.

 

Thanks for the advice guys, really appreciate it - i can't seem to find that complete ebc kit you linked to sprock available in the uk, and i don't really want to import unless i have to (got stung a fortune on import duty a few years back on some D&D silencers for my old zzr1100!) Been looking around at replacement clutch plates and found this on ebay. It's just the friction plates though.

CK1248 EBC Clutch Kit - Honda CB1000 Big One, CBR1000F | eBay

David Silver honda spares list genuine clutch plates (but not currently in stock)

Wemoto do "Gecko" cork type frictions plates but i've never heard of the brand....

Are these bikes particularly hard on clutches in general? ( i know a lot of it is down to how the bike is ridden / treated!) How long should a clutch on average last on a 1kf?

Interesting to hear the views on diesel oil? from my limited knowledge of oil, i only ever use bike specific semi-synth usually, i have heard car oil is not good to use in bikes.

 

If you are doing a clutch job go the whole hog man especially new springs most important, tired springs will glaze up a new clutch quick enough imo.

Sorry about that here's the link to bitzforbikes ebay UK - the whole srk kit - bit pricey

and at wemoto

and cheaper still at ebcdirectuk

other item you'd need is the clutch cover gasket

 

About a week ago i ordered new clutch friction plates (had to get pattern as genuine were on back order till april/may), springs, gaskets and slave seals from david silver and they arrived today.

So i pulled my finger out and got cracking and rebuilt the leaking clutch slave cylinder. The new slave piston seal looked like it had quite a bit more rubber on the lip than the old one so i think it was long overdue replacing. The old one had wear grooves and marks and was pretty bad.

I cleaned and polished the slave piston and housing as there was a lot of crap and corrosion on them. Put it all back together, bled it up (dead easy with a large syringe with a bit of tube!) and clutch action is a lot smoother with no leaks - very relieved!

Got fresh oil on order and will be replacing the clutch plates and springs when it turns up - looking forward to getting it done and being able to ride it with no slippage, it's been spending far too long in the garage sat doing nothing for my liking!

 

I've read most of the clutch issues threads using the search but I'd like to ask 1 question. I did change the oil yesterday from...well...black to Conventional 10w-40. Getting on it at 7-9 grand with a load it seemed to slip. Sixth gear between 9 and 10 grand there was a slight slip too. A friend is an EBC dealer so I have springs and disks coming. I'm planning on glass beading the plates. Could it be the oil?