Topic: Master cylinder rebuild kit issues

[benjamin550]

Well, I thought I was going to get to ride my bike this weekend for the first time, but alas, more problems came up when I went to put the master cylinder back on. I rebuilt the MC with a kit I bought from a member here. It was an off-brand kit (cant remember which brand) and everything fit in fine, but when I went to bleed the brakes it started leaking. I took it off to find the problem seems to be the last rubber piece that goes on. Not sure what it's called but it is the piece that is held on by the last clip you have to put in and compresses when the lever is pressed. Anyways, it seems that the problem is the base of this piece, the flange that the clip pushes against, is too thick to allow the clip to properly seal it off. When i removed the old one from Honda the clip seemed to be inside the rubber so when it was seated in its grove it pushes the rubber against the walls creating a seal. This one is made differently and the clip wont make a good seal. Since all of the other parts are good, is there any way to buy just this piece of rubber and clip, or do I have to buy another whole rebuild kit? I would really prefer not to as they are about 40 bucks from Honda, and I really don't want to try and get that circlip out again. I would almost be tempted to buy the whole master cylinder from David Silver Spears for about the same price as a rebuild kit.

Thanks

[Terry in Australia]

Yeah mate, the last rubber piece that goes on is the rubber boot that fits around the lever end of the piston, basically the spring and piston goes in first, then the circlip, and then the boot. if fluid is leaking past your boot, the seal on the piston isn't sealing, as the boot is to stop dust and crap from getting in, not for fluid from escaping.

I just bought a new after-market MC complete with lever from DSS for around 40 bucks, and it looks great, tonight I'm hooking up the caliper so I'll let you know how well it works, but if it does, I'll never rebuild a MC again. Cheers, Terry.

[benjamin550]

Thanks, please do let me know how it works. So, I wonder what I did wrong. Besides getting the criclip out, everything else seemed pretty straight forward and easy. The one snag I had was deciding whether or not to put in the check valve that came with the rebuild kit. Mine did not have one originally and after searching around a little bit on the forum I found it is common for the kits to include these, but it isnt necessary to put this in. Could this cause my problem? When i put the MC back on, it did build up pressure in the brake lines so I know it works. There was just a little seepage out of the lever end.

[BeSeeingYou]

If there is a next time get the OEM kit.  There may be minor differences in the piston depending on the year and these generic one size fits all sometimes don't.   The check valve was not used after 76 I believe. 

[dave500]

im interested in those complete m/c assemblies aswell terry,i emailed silvers and asked if they used the same rebuild kit but they didnt know.i think its imperial bore.

[BeSeeingYou]

im interested in those complete m/c assemblies aswell terry,i emailed silvers and asked if they used the same rebuild kit but they didnt know.i think its imperial bore.

It's from the U.K.  Don't you mean Imperial Boor?

[dave500]

boer?

[BeSeeingYou]

boer?

I think that's Dutch.
more along this line.  I can't invite a boor like him to dinner! He'd offend the other guests.

[Terry in Australia]

Well I hooked up the caliper tonight after work and using one of those neat speed bleeder bleed screws they sell on EBay it only took me 20 minutes max (maybe less, I was so shocked I forgot to time myself) to have a nice hard lever! (well two actually, the other one was in my pants, I was so impressed)

The DSS MC isn't an exact replica of the OEM item, it's got some vertical ribs on the body of the fluid reservoir and a slightly different cap, but (even though I haven't ridden the K2 yet) it feels good, and it looks good enough not to be noticed by anyone apart from the most anal of CB connoisseurs. Fine for a "daily rider", but if you want to enter your bike in a show, you'll have to spend a tad more on an OEM item. Cheers, Terry.