the work step that I thought of to be the easiest one in overhauling the clutch, turns out to be the most annoying one…bleeding that bloody hydraulic system.
New friction plates, new steel plates, new clutch spring, new gasket,…why not cleaning the reservoir and substituting that dark brown liquid in it!
It is not the first brake or clutch system I´m working on and so I wasn´t expecting any difficulties. But now the clutch is not really disengaging, i.e. in first gear with pulled lever I have to pull forth and back and then it is free.
It is as if there is still air in the system, but bleeding it again and again showed nomore bubbles.
Needless to say, that it worked perfectly with the dark brown liquid, whatever it was…
Does anybody out there have any further advice?
Thanks a lot!
I had similar issues when I bled mine. Evenually I bit the bullet and bought a 100ml syringe and length of plastic tubing.
Put some clean fluid into a clean container, deep enough to cover the end of the tube. Put the tube on the bleed nipple, and fill it up with fluid. This may take a while to ensure that there are no bubbles in it.
Put your finger over the end, and immerse it in the bowl of fluid.
Pull the lever back to the bar, and crack the nipple.
Release the lever with the nipple cracked.
Operate the lever until you see no bubbles in the tube, and none returning to the reservoir.
Tighten the nipple.
Now bleed it in the traditional way (lever in, nipple open, nipple closed, lever out) two or three times to ensure that there is no air coming out of the plastic tube.
You should now find that the system is air free.
After my new clutch was fitted, it didn’t appear to disengage right off the bat. It took about four attempts at putting it into gear before it was hassle free.
Even now, if it’s been standing for a week or so unused, the first gear engagement will result in it lurching forwards, stalling the engine. Apparently (according to the local dealership) it’s because of stiction between the plates because of the thin film of oil between them. I’m not convinced about that, but they know more than I do.
Hope this helps and good luck!
You may have already looked at this.
are you sure the slave cylinder piston will come out if you gently squeeze the clutch lever? when removed from the clutch cover.
Have you already replaced the bleed nipple of the slave cylinder with a new one?
The old bleed nipple may not close properly because the thread is worn out.
I battled with Honda clutch slave cylinders on different models forever and I’m convinced that the design of the piston seal, tapered, allows air to easily pass into the slave cylinder from the engine side during the bleeding process (excuse the pun). If too much suction is applied to the bleed nipple air will actually be drawn into the slave cylinder past the piston seal.
Trying to push air out of the system from the clutch lever is difficult because of the length of the run and the direction, downhill. Certainly on the VF750 the other issue is the highest point of the system is the banjo bolt on the master cylinder so it is necessary to unbolt the master cylinder from the handlebar and turn it so the master cylinder is above the banjo bolt then press the lever a couple of times to get any stuck air to rise into the master cylinder.
The other thing you might want to consider is a vacuum bleed tool. UK eBay has them for sale for £14.39, item number 312771796795. This tool has saved me countless hours bleeding brakes on very reluctant systems, it’s one of those tools you wonder how you ever managed without one. BUT… do not use a lot of vacuum as air will be drawn into the slave cylinder past the piston seal and while it looks as though you’re bleeding the system you’re not.
Thank you for all your answer, gents!
I had a vacuum bleeder tool, which i bought several years ago at a POLO store in Hamburg, and I would describe it as crap. Threw it away last week since it caused me pain too often.
Then i dismantled the slave cylinder to check if everything works smooth, and it does.
I´ve tried to bring it to the highest position but that would require the slave cylinder to be pushed through the gap between the frame and engine which is too narrow.
Meanwhile i had several more " bleeding actions" and it is astonishing that there are always some small bubbles appearing after a couple of days. The clutch works quite satisfying at the moment. A bike which stalls the engine when the first gear is engaged is absolutely no option. I don´t want to imagine what kind of stress that means for each engine part.
I will check for the 312771796795 tool recommended by Chris and buy a syringe as well. Be prepared…
I only need to get the master cylinder reservoir to be higher than the master cylinder banjo bolt on the VF750, hence the need to unbolt it from the handlebar and tilt it. The outlet port from the master cylinder points upwards so air gets trapped at the highest point.
I used to have a nightmare bleeding the brakes on an old GPZ900, it could take literally hours, that vacuum tool makes the job 20 minutes tops.
The other thing that used to catch me out was trying to bleed the clutch with the slave cylinder not bolted to the bike. This is hard to explain but if you let the slave cylinder spring push the piston forward, rather than fluid pushing it forward, the tapered shape of the seal allows air into the slave cylinder.
I do my bleeding manually, the good old pump away method did it yesterday with the VF clutch and worked very well, just need to watch that your reservir doesnt run out of fluid…
I will probably do brakes next week, depending on how my other projects go…