Author Topic: master cylinder rebuild headaches (Read 2271 times)

78whiteorbs · « **on:** July 31, 2014, 08:31:12 PM »

About to through in the towel and buy a new master .
Read all the threads I could find and seems very straight forward. Snapped everything into place and can feel pressure bothe ways when pumping the piston but its not enough. Shoots a "mist" that looks like a plume of smoke out of the end of the master with the line off ...shouldnt the pressure blow your thumb off the business end? Pissin me off this is the only thing keeping me off the road ....

goldarrow · « **Reply #1 on:** July 31, 2014, 08:35:57 PM »

Need good cleaning still

bjbuchanan · « **Reply #2 on:** July 31, 2014, 08:58:03 PM »

Try it on the bike if you trust your cleaning job. I had a bell of a time trying to prime mine unhooked.

All hooked up only took a couple extra mins to purge

Stev-o · « **Reply #3 on:** July 31, 2014, 09:20:40 PM »

Doesn't pay to rebuild a master, buy one from DSS.

mono · « **Reply #4 on:** July 31, 2014, 09:44:40 PM »

I agree with bj

Dave Voss · « **Reply #5 on:** July 31, 2014, 10:13:23 PM »

Quote from: Stev-o on July 31, 2014, 09:20:40 PM

Doesn't pay to rebuild a master, buy one from DSS.

This is true. I rebuilt my original master cylinder with all new parts, the bore looked good, should be no problem right? Wrong. It bled okay after installation, but wouldn't hold light-to-moderate pressure, and required release and another grab to keep steady braking. I took it apart and looked for signs of trouble, but couldn't find any, so I ordered a DSS unit and never looked back. With the original reservoir cap screwed on, it looks like it's always been there. For the price, its really a great option.

goldarrow · « **Reply #6 on:** July 31, 2014, 10:18:10 PM »

All my bikes are still running on stock MC

dhall57 · « **Reply #7 on:** August 01, 2014, 01:53:51 AM »

I rebuilt my original KO, K6 and Wang m/c and have no problem. Firm lever and brakes are fine. But of course rebuilt calipers also and put on new brake lines and pads.

seanbarney41 · « **Reply #8 on:** August 01, 2014, 03:31:27 AM »

After bad experiences, I usually try to avoid master cylinder rebuilding...props to those with the patience to do it right.

dave500 · « **Reply #9 on:** August 01, 2014, 03:36:26 AM »

some have put the seals on backwards?or damaged them during install?if your starting with a pretty good core then its fine,if you have a grungy white powdered encrusted stuck lump with rusted internals get a new one,i think the new repro ones are great value!

78whiteorbs · « **Reply #10 on:** August 01, 2014, 06:16:06 AM »

Well its definately not a crusted up nightmare. Looks brand new never used ironically. I got it in a box of parts for a 400f with like three oem rebuild kits. The bore was perfect .....normally I dont waste the time it takes cause its just not worth it to me . Got a link to the one you are talking about steve-o?

Stev-o · « **Reply #11 on:** August 01, 2014, 06:29:51 AM »

$45 at DSS Orbs.....

https://www.davidsilverspares.com/CB750K4-FOUR-1974-USA/part_123914/

78whiteorbs · « **Reply #12 on:** August 01, 2014, 06:33:57 AM »

Thanks, does that ship from america?

Stev-o · « **Reply #13 on:** August 01, 2014, 06:38:33 AM »

Quote from: 78whiteorbs on August 01, 2014, 06:33:57 AM

Thanks, does that ship from america?

Yes, PAw

78whiteorbs · « **Reply #14 on:** August 01, 2014, 07:03:47 AM »

Just saw the flags on web banner...just ordered.thanks

jamesbekman · « **Reply #15 on:** August 01, 2014, 08:39:34 AM »

Im waiting for mine to arrive too! Their price for pads and shoes cant be beat either.

-James

Johnie · « **Reply #16 on:** August 01, 2014, 09:27:48 AM »

Hmmmm...I rebuilt all mine and the only issue I had was needing my Mighty Vac to get it to bleed. Could not get it to bleed out without the vac. I also honed the bore on the MC which many do not do. So far so good. Hope you get yours sorted out.

78whiteorbs · « **Reply #17 on:** August 01, 2014, 09:40:51 AM »

I did it , it will sit on a shelf in mockery of my inferior mechanical talent in the realm of rebuilding master cylinders. I put the vacuum on it and at first it started to bubble and bleed out like normal and then nothing

dave500 · « **Reply #18 on:** August 01, 2014, 01:59:21 PM »

I had mine brass sleeved.

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Author Topic: master cylinder rebuild headaches (Read 2271 times)