Topic: Is this an issue? (Pics)

[BigBoi]

Well, that's a strange question because it's obviously an issue.

I'm trying to sort out the leak I'm getting from my master cylinder and I was hoping you all could help. I rebuilt it with some parts that were included with the bike (still in the bag from Honda). I put it together properly (took it apart twice since).

Can someone tell me how tight the cup and secondary cup are supposed to be to the edges? My issue is that the second I put fluid in the reservoir, it comes out the brake handle end, and I mean really coming out. It's pouring through the larger hole in the reservoir through both cups (Or maybe just 1?). Isn't the primary cup past this hole therefore leaving just second one holding in the fluid? There's play in the piston towards the sides. :/

Thing is, the sides of my master cylinder look just fine. No scores, nothing. So I did a lot of searches, and it looks like my second seal isn't the same as I've seen online. Is it possible that I have the wrong seal?

There isn't supposed to be play from side to side with the piston right?

Thanks all...

[Spanner 1]

Got to be wrong size seals as the seal on the piston is what stops fluid out of the bore at the lever end, it's on the right way too , from your pics. Should not be any 'play' with the piston and seals installed IMO.....

[kghost]

You may have a master cylinder off a different bike.....its not uncommon

[TwoTired]

Show us a pic of the parts arranged as you would put them into the bore.

You have de-glazed the cylinder bore, right?

[BigBoi]

Show us a pic of the parts arranged as you would put them into the bore.

You have de-glazed the cylinder bore, right?

I did quite a bit of research before I installed it. Even watched that video walktrough posted online. Anyway, the picture below is how I installed it.

I also did some more investigating. It looks like I might have the wrong rebuild kit. I brought up both the kit for the CB750 SOHCs and the CB750 DOHC on old bike barn:

Correct:
http://www.oldbikebarn.com/Honda-CB360-CB750-Front-Brake-Master-Cylinder-Rebuild-Kit?sc=12&category=52219

Incorrect:
http://www.oldbikebarn.com/Honda-Front-Brake-Master-Cylinder-Rebuild-Kit_4?sc=12&category=52465

See how the little second seal isn't the same? Well if you have a look, it seems that I have the 80's version.

I've got a new kit coming in from Honda today, so I'll try it. I must have some part wrong because I'm not talking about a little leak here...it's majorly coming out of there.

Thanks all...

[BigBoi]

In case anyone is following this, I'm embarrassed again to let you know my findings.

My master cylinder is from a Kawasaki. It's actually a 5/8, which is why my 14mm piston isn't working.

I don't know what to do now. Is it ok/good/recommended to use this master with a single disc setup? I don't plan on adding a second disc/caliper.

If not, I'm thinking about either getting another stock master from a Honda, or going with the Partsnmore single disc master cylinder.

Thoughts? Comments?

[ev0lve]

5/8's is 16mm. Yes, it'll work. The difference will be mostly in how it feels at the lever. I have a 16 on duals on a 750 and it still feels pretty wooden - owing to the piston size in the caliper I would guess. There are some really nice discussions of the why's and wherefores of MC piston size vs caliper piston(s) around here but Honda probably got it right the first time 

If you're not a stickler for stock any 14mm will do but at that point I'd buy new not used.

[scunny]

heres an explanation and chart.
http://www.vintagebrake.com/mastercylinder.htm