Topic: Rear Master Cylinder....I give up !

[MOONDOGNYC]

So I bought a rebuild kit for my 77 CB750f SuperSport.   The problem is that the circlip is rusted in place and in peices. It looks like someone may have tried to gouge it out too,as the top of the bore appears scratched.
 So I give up....I can't get it out....Now what ??  Please help.

[Johnie]

Had the same issue. Used some rust disolving spray...PB Blaster and let it work. Then used mechanics picks to finally get it out. One tab of the circlip had broke off too.

[MOONDOGNYC]

SHould have mentioned that I did that too...   losing my mind with this little $%#@# part....

[nevernoluck]

Kroil works good for soaking what pb blaster doesn't do good enough at. Other than that without seeing what you are dealing with and not having done that exact part before but using my past experience, picks or sacrifice a small straight screwdriver and either grind it down or bend it to suit your needs might help too as they tend to be a little tougher. Show me a pic and I might have other ideas too.

[skidooextreme]

From my cb750c.com site

Credit goes to Tourmaster


Here's an interesting bit of information that's being passed around our vintage motorcycle group here in Saskatchewan. This may have come up before, but if not, makes for an interesting alternative to breaking free those nasty seized up components ..........

Machinist's Workshop magazine tested penetrants for break out torque on rusted nuts with significant results!

They arranged a subjective test of all the popular penetrants with the
control being the torque required to remove the nut from a
"scientifically rusted" environment (obviously a BIG nut!).

Penetrating oil ...... Average torque

None ....................... 516 ft lbs

WD-40 ................... 238 ft lbs

PB Blaster .............. 214 ft lbs

Liquid Wrench ..... 127 ft lbs

Kano Kroil ............. 106 ft lbs

ATF-Acetone mix....53 ft lbs

The ATF-Acetone mix was a "home brew" mix of 50 - 50 automatic
transmission fluid and acetone. Note the "home brew" was better than any
commercial product in this one particular test. Our local machinistgroup mixed up a batch and we all now use it with equally good results.


I have also heard of people putting sea foam in seized engines and it working in a few hours.....try that in there

[nevernoluck]

Glad to see kroil not too bad from lab testing compared to the rest, just knew it worked for me but that home brew sure looks good and cheaper.

[MOONDOGNYC]

Giving it a try....let you guysknowthe outcome. Thanks !

[phil71]

I have seen those results floating around. They're intriguing, but I can't figure out how they managed the controls for the test. It would seem a huge task to make a bunch of bolts rust the same exact way for a test like this.

[dusterdude]

Damn,that makes me want to cry,im a pb man all the way

[JohnG]

heat might help in addition to the oils mentioned.

Every one I ever worked on broke. Too much moisture near it.
 
I recall taking a small hammer and thin screwdriver and tapping sideways  (as much as that is possible) which caused the clip to move sideways in the groove a little, which got things going.

Once I used the drill press and a very small bit and drilled a new hole in the remants of the clip, which allowed me to get a pic into it and pry it out.  Dinged up the groove a little in the process but nothing that did not keep the new one from doing its job.

[xsmooth69x]

blow torch

[Killer Canary]

There's a vintage motorcycle group in Saskatchewan?

[Don R]

I broke off both tabs on one when I first got back into sohc's. I finally drilled a small hole from the back side directly into the groove where the snap ring sits. The bit caught the snap ring and popped it right out. I hadn't planned on it working that well but the M/C's  still in use several years later. This was a front but aprocedure that might work for you, use your own judgement. When you are done, don't overstroke the cyl when bleeding. You can let fluid back into the snap ring area. There was a bulletin about it years ago.