[Jools]

Yes, you'll have to fix the slave cynder seal before bleeding the clutch through again otherwise it may bleed through but you'll have the same problem very quickly. You'll probably find the easiest way is to replace the slave cylinder completely because the cylinder bore is often scored. If your current slave is sort of flat topped with a smaller slightly raised boss in the centre of it you have the old type slave. Replacing this with a newer design slave (one that's got a big star shaped 'torx' head in the centre) will be much more reliable - the design is improved so that road dirt and crud from the chain don't get into the slave so easy.

Once you've sorted that out you can bleed the clutch. I've found that the problem with clutches is that once the system starts to get primed the slave cylinder starts to move (this is of course what you want but it makes bleeding more difficult). As Glyn says, the system will also be full of air.

You do want to take the rubber diaphragm out of the reservoir. This is here because you do need atmospheric pressure to act on the fluid in the reservoir, otherwise as the fluid level dropped as the clutch self adjusts there would be a vacuum in the reservoir stopping the fluid getting through to the master cylinder. However, brake and clutch fluid is very hygroscopic and absorbs moisture from the air. You don't want any water in the fluid because under the heat of the clutch this will boil off and effectively give you the same problem as if the clutch was full of air. So take it out to bleed the clutch and don't forget to put it back in.

I've found that with a completely empty system the master cylinder doesn't want to pump fluid until you've primed it first. To do this, get a whole heap of absorbent material under the banjo at the master cylinder then just crack the banjo bolt open until fluid can just seep out. Squeeze the lever SLOWLY so that fluid just seeps out between the cracks and doesn't spray everywhere. When the lever is back to the bar, tighten the banjo and release the clutch lever. Repeat this process three or four times and the master cylinder should now be free of air.

Next, repeat Glyn's instructions and you'll drive any air out of the line. I've sometimes found that priming the slave cylinder helps as well. I do this by taking the slave off the bike, but leaving all the hydraulics connected. I squeeze the clutch lever so that the slave piston extends, then l let go of the clutch lever, open the bleed nipple and squeeze the slave piston back in with my thumb, again you only usually need do this two or three times.

Hope that helps and good luck


Oh yes, and don't forget that hydraulic fluid is nasty stuff that'll eat paintwork and doesn't do your skin much good either, so wear latex gloves, have plenty of rags around wherever it might splash and have plenty of bike cleaner and water standing by to sluice any splashes off ASAP. But don't do what I did once - faced with a spurt of fluid that hit my petrol tank I grabbed the hose and rinsed it for ages. That was fine until I realised that I'd grabbed the hose in panic before I had put the top back on the fluid reservoir, I'd then got water into the reservoir, contaminated the fluid and had to start all over again.