I need a bit of help please, my mates got a Yamaha XJR1200.Going to have to explain from the start so bear with me the story starts when he fitted new chrome reservoir caps this involved removing the plastic insert that holds the diaphragm in place some months later he noticed the reservoir was weeping fluid and the clutch was creeping with the lever right pulled all the way in took the cap off and found the diaphragm had expanded to twice its original size, I suggested this might be because the plastic plate wasnt in place and allowed the diaphragm to expand at a greater rate than it would have if the plastic cap was in place, so he buys a new diaphragm and new reservoir caps so the plastic plate is back in place, this was a week ago he rang me today to say his reservoir was weeping again the clutch creeping again and the new diaphragm had expanded to twice its size again He spoke to Sale Yamaha they told him they havnt heard of this problem before and it wasnt a bad batch of diaphragm's any ideas
i think you may have a problem with the type of fluid you are using m8 - did you change it for something else... sounds like its incompatible with the rubber of the diaphragm.. you could try changing the fluid for a proper dot4 type - i dunno, sounds like you may have like transmission fluid in or something with a detergent additive? can't see how just replacing the top would affect the diaphragm or give you the creeps? fluid change for what it costs.. maybe buy more than you need and flush it all through proper. afaik the plastic holder just seals with an o ring - maybe you nipped it when you refitted it? rather than buy a seal kit you could take the old o ring down to a local eap or bearing power centre (theres one on woolston granges) & get it matched up with something but make sure its viton rubber not nitrile should only be a quid or so. *maybe the fluid is getting on top of the diaphragm and it's being forced down when you pump the lever and is stretching the rubber - did you put it all back together proper, ie plastic tub, diaphragm, then the diaphragm cap, then the lid? see how the clutch works with the lid & diaphragm off, with the tub open... obviously not go for a ride lol, i mean just pump it and see what happens
He used Comma Dot 4 brake and clutch fluid from the local Garage which is the same one I use and mines ok ???,their is no O ring on the plastic cover it's designed so the diaphragm sits in a recess around the edge of it to create the seal hence why I thought that was why it was weeping
you mean you fitted it without the plastic top that sits on top of the diaphragm, under the cap? if so i reckon thats the problem cos it should seal the diaphragm on the top? i dont have the same bike, just going of all the other master cylinders ive seen... where in wton are you? bit odd as if you have put it all back the way it was you shouldnt really have a problem?
Thanks for helping out mate it's appreciated Firstly let me clarify it's not my bike its a mate who lives in Rochdale,the chrome caps he bought are not designed to have the plastic cap thats where the problem started,so he thought buying a new diaphram and refitting the plastic and new top caps would sort it but it's just distorted the diaphram again also he refreashed the Dot4 fluid with new when he put it back together as I said its only been a week and it's started leaking again and the clutch is creeping
Ok got a call today,my mates found a complete master cylinder on the Bay he's decided to go for it. If I think on i'll update this post if it works Thanks Vvtr for your help :thumbsup:
yeh let us know how he gets on - bit of an odd one that eh :S just another thought.... what pads is he using & any glazing on the discs? was wondering before if he could be boiling the fluid?
