dgp

Hey, bit late, but you are after the 25mm one

After a couple of days, the clutch went back to having the same issue. Today I received the new OEM rebuild kit, installed it and now have a working clutch. You can see in the photos below the big difference between the old and new seals.

Thanks DannoXYZ, I will put the kit in when it arrives this week, best thing is to just renew it now and press on. I appreciate all the responses and assistance from the group. Thank you.

So, after cleaning up the bore with P2000 ( I live in a town of 30,000, and no one sells anything above P2000), and Brasso, I put it back together and still no joy. I dismantled it again and took the master to a machinist to talk about re-sleeping it. I also ordered a rebuild kit. The machinest said he had seen much worse still operating and made a point of telling me he thought the piston rubber was too flat, he thought it should have more of a tapered edge. Pic of a new one below (courtesy of CMSNL). Mine is certainly was more round, without the edge on it ( sorry didn’t take a pic before installing). Over night I soaked the piston rubber in my mix of wintergreen oil/ isopropyl alcohol that I used to rejuvenate my carb insulators. I did this as it is known to swell rubber. This morning, I put it back together again, piston rubber has swollen and required some grease to slide into the bore, hey presto, I now have pressure. The master is still on my bench, I will leave it there for a few days to see if the rubber contracts and loses pressure, but I am happy I found the issue. I also noted that there is a small tear around the sealing washer at the base of the rubber boot that contacts the circlip. I will most likely pull it all apart and put the kit through it anyway, just to be sure.

Righto, I used a bolt in the master cylinder to see if it was holding pressure. Sadly no, no it wasn’t. Pulled the master apart, and found that the bore was quite bad, it looked as though the previous owner had let the fluid drain out and dry up in the bore, leaving corrosion spots. So, I got some 2000 grit wet/dry sandpaper, wrapped it around a 12mm fuel hose, covered it in brake fluid and reemed out the bore. It looks heaps better but only time will tell. I need to buy some silicone grease tomorrow and re-assemble the system to see if it will hold pressure. I have attached some before and after pics below, sorry, not the best quality. Thanks for all the suggestions guys. If it holds pressure great, if not, I will have to find someone who can re-sleeve the bore, then I will buy the rebuild kits as suggested by DannoXYZ, and refresh the whole system. If I go down that path though, I think I will just buy a new slave cylinder and rebuild the master.

Thanks for the explanation DannoXYZ, I will go and buy some more appropriate circlip pliers today and take the piston out of the master cylinder so I can inspect it and decide on next steps. If the bore is scored, can I repair/sand it, or do I need to replace it?

I have dismantled the slave, seal looks good. I have dismantled the lever, removed the rubber boot and rod, all looks good. I was going to remove the piston but my circlip pliers didn’t have enough reach to get down to it. So, in answer to Grum, no I have not inspected the bore ( assuming you mean on the master side of the circlip). Can air get past the piston seal without leaking fluid, that would be the only reason to inspect the bore wouldn’t it? Doing the slow lever pull, I am still getting very small amount of air coming up through what I think is the larger hole in the master cylinder, it’s confusing me though as I must have done the lever pull 100 times and can’t wrap my head around that much air being in the system so think that it must be getting in somewhere, but I have no leaks. The clutch rod is free and moves easily, I will re-grease it though when I get this issues solved when putting the slave back on. Right now I am thinking come back to it and cycle the lever every so often, not too much because I may even be cavitation the oil and creating the problem. Maybe I need to look at replacing the nipple on the slave cylinder, I did notice that it has particularly wide pitch threads which I thought was odd.

Hi everyone, First post, so hi to all, I have been enjoying reading the content of the forum and have recently purchase a 1995 VFR with 73,000km on the clock. I had one brand new back in ‘96 and have come to my senses and bought another one. I have been doing all the regular maintenance for a new to me bike but am having terrible trouble bleeding the clutch. I have blead about 1.5lt of brake fluid through using a compressed air bleeder ( I did do it the traditional way first with no joy), burped the banjo bolts at the master and slave (no air evident), raised the master above the banjo and tapped it to dislodge air while pulling the lever in slowly and letting it go quickly. I have gone to the extreme and removed the master and slave from the bike to try and bleed the system. If I pull the lever quickly, I get pressure and the clutch operates, if I pull it slowly, it pulls all the way in without engaging the clutch. I have covered the slave bleed nipple in grease (around the thread) to ensure no air leaking in through the threads. I have linked a video below, and I hope some kind VFR owner has some insight into what the heck I am doing wrong.