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Discussion Starter · #1 ·
I have rebuilt my MC, cleaned it up....and yes, I have cleaned that little hole where the returning fluid comes through. It is very small though, I could not find anything this small to poke through....and I am doing my carburetor a la Larry's instruction. When I hit the hole with the carb spray nozzle, I could see fine mist coming out the other side. In my world that means "clean passage". Anyways, when put all together the piston doesn't retract. First, I thought it is the piston causing trouble. So I pumped it out as far as I could without popping it out and cleaned it. Then was going to to push it back in with a C-Clamp and it wouldn't move. When I opened the bleeder nipple, it would slide back in. If I had not just cleaned that return hole in the MC I would have guessed to be the problem. Does anybody have an idea what it could be?
 

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While I'm not a pro on brakes it does sound to me as if you need a set of caliper seals.

Odd thing about those, in time brake fuid absorbs water and oxygen and attacks them.



Just get them, Matt @ TAS probably has them with free shipping if you have a cell that can call non-800#'s. 2-3 days you'll have parts.



Can't be any different than rebuilding the caliper on a car. Clean the heck out of everything but don't introduce any scratches. Lube the heck out of the new seals with nothing but brake fluid then carefully and patiently guide them back into place.
 

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I have rebuilt my MC, cleaned it up....and yes, I have cleaned that little hole where the returning fluid comes through. It is very small though, I could not find anything this small to poke through....and I am doing my carburetor a la Larry's instruction. When I hit the hole with the carb spray nozzle, I could see fine mist coming out the other side. In my world that means "clean passage". Anyways, when put all together the piston doesn't retract. First, I thought it is the piston causing trouble. So I pumped it out as far as I could without popping it out and cleaned it. Then was going to to push it back in with a C-Clamp and it wouldn't move. When I opened the bleeder nipple, it would slide back in. If I had not just cleaned that return hole in the MC I would have guessed to be the problem. Does anybody have an idea what it could be?


First off did you totally disassemble the MC or not? What you have said isn't real clear. If not you need to do so.



You should never need a C-clamp to push it back in ... it should slide in with just a firm push.



I have a piece of a guitar string I use on the small hole.



If your MC is all clean and reassembled and the wheel still doesn't spin easily, you may need to rebuild the calipers and/or replace the brake lines.



With age original brake lines can deteriorate and swell closed so you only have a one way flow of brake fluid and the brakes never totally release.



Now, when you say the piston doesn't retract I assume your mean it doesn't return tot he release position? That may be due to you putting the piston back in with a C-clamp and probably wrecking the rubber piston.



Take the MC fully apart and see if the rubber piston is ruined ... and let us know if it is damaged so we can advise you what to do next.
 

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Discussion Starter · #4 ·
First off did you totally disassemble the MC or not? What you have said isn't real clear. If not you need to do so.



You should never need a C-clamp to push it back in ... it should slide in with just a firm push.



I have a piece of a guitar string I use on the small hole.



If your MC is all clean and reassembled and the wheel still doesn't spin easily, you may need to rebuild the calipers and/or replace the brake lines.



With age original brake lines can deteriorate and swell closed so you only have a one way flow of brake fluid and the brakes never totally release.



Now, when you say the piston doesn't retract I assume your mean it doesn't return tot he release position? That may be due to you putting the piston back in with a C-clamp and probably wrecking the rubber piston.



Take the MC fully apart and see if the rubber piston is ruined ... and let us know if it is damaged so we can advise you what to do next.


David, I did not put the c-clamp on the MC piston. I put it on the caliper piston. And yes, I have rebuilt the MC. I think the problem might be with the caliper.I just got a little confused when I was able to push the caliper piston all the way back after opening up the bleeder valve. I guess I am looking at buying yet another rebuild kit. I am getting a little tired of buying these expensive rebuild kits. Oh well, that's what you get when you buy a 30 year old bike which has been parked for most of its life. 30 years old and 8000 miles on the speedometer. Yikes!!
 

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Discussion Starter · #5 ·
David, I did not put the c-clamp on the MC piston. I put it on the caliper piston. And yes, I have rebuilt the MC. I think the problem might be with the caliper.I just got a little confused when I was able to push the caliper piston all the way back after opening up the bleeder valve. I guess I am looking at buying yet another rebuild kit. I am getting a little tired of buying these expensive rebuild kits. Oh well, that's what you get when you buy a 30 year old bike which has been parked for most of its life. 30 years old and 8000 miles on the speedometer. Yikes!!
Also, does anybody know, if the dual piston caliper of a 83'cx650 would work on a 80' Deluxe without major modifications? I have one lying around and I might just rebuild that one instead of my single piston one.
 

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David, I did not put the c-clamp on the MC piston. I put it on the caliper piston. And yes, I have rebuilt the MC. I think the problem might be with the caliper.I just got a little confused when I was able to push the caliper piston all the way back after opening up the bleeder valve. I guess I am looking at buying yet another rebuild kit. I am getting a little tired of buying these expensive rebuild kits. Oh well, that's what you get when you buy a 30 year old bike which has been parked for most of its life. 30 years old and 8000 miles on the speedometer. Yikes!!






The other thing you might consider is just buying a new master cylinder. It doesn't have to be one for a CX or GL specifically. I'm using a chromed MC that was marketed as a fitting a Yamaha something or other. The brake doesn't know the difference.



I got mine from this guy: USA Motorcycles Inc. The master cylinder in the ad will work for your CX even though he's not advertising it as such. He has plenty of others that will work in different finishes. The buy it now price is $79.99 or you can take your chances on an auction bid... but I wouldn't bid *more* than $79.99. Shipping is another $12 or so.



A lot of folks here have had good luck with these. The few who had problems said that he would swap out MCs without argument. These are all brand new MCs so there's no screwing around with 30 year old parts.
 

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David, I did not put the c-clamp on the MC piston. I put it on the caliper piston. And yes, I have rebuilt the MC. I think the problem might be with the caliper.I just got a little confused when I was able to push the caliper piston all the way back after opening up the bleeder valve. I guess I am looking at buying yet another rebuild kit. I am getting a little tired of buying these expensive rebuild kits. Oh well, that's what you get when you buy a 30 year old bike which has been parked for most of its life. 30 years old and 8000 miles on the speedometer. Yikes!!




IF the banjo is connected to the Caliper and MC with fluid in it the only way to push the caliper pistons in is to release pressure ( the bleeder) If the caliper is not connectd to anything, it would indicate a restriction or obstruction between the banjo connection and the back of the piston.



With the caliper off the bike, and no fluid in it, the piston should go in fairly easily. The damm seals are a rubber ring shaped like a channel. If one of these is torn... it may be partially in the bore.



There is no doubt that brake lines do not last this long. Replacing mine fixed the issue of a sticky pot for me.





I do not think the mounting bosses on the fork legs are the same 'tween single and double pot calipers.
 

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Based on your experiences to date, if the caliper piston won't be pushed in until you release the pressure via the bleeder, the fluid is holding the piston out. The only relief for the fluid to return is via the tiny hole you are familiar with. A mist from it would seem too little flow to call it "open", and a very small bit of debris could have reclogged it. I would look at the tiny hole again. It's where the fluid has to release to permit the caliper piston to return. Now, where the debris is originating may be the next chapter.
 

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Discussion Starter · #9 ·
Based on your experiences to date, if the caliper piston won't be pushed in until you release the pressure via the bleeder, the fluid is holding the piston out. The only relief for the fluid to return is via the tiny hole you are familiar with. A mist from it would seem too little flow to call it "open", and a very small bit of debris could have reclogged it. I would look at the tiny hole again. It's where the fluid has to release to permit the caliper piston to return. Now, where the debris is originating may be the next chapter.
I have already invested over $60 into MC (rebuild kit, new fluid cup and diaphragm, new brake lever). This will be a lesson for me. Next time I just buy aftermarket MC.

It's just nice to keep it somewhat stock.

Today, I took out the bleeder nipple and it was really rusty at the bottom. Shows me this caliper has been sitting with water in it for a while. I will take the caliper apart for cleaning.

I still would like to find out if the CX 650 dual piston caliper would be a simple bolt-on.



Thanks for the help
 

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David, I did not put the c-clamp on the MC piston. I put it on the caliper piston. And yes, I have rebuilt the MC. I think the problem might be with the caliper.I just got a little confused when I was able to push the caliper piston all the way back after opening up the bleeder valve. I guess I am looking at buying yet another rebuild kit. I am getting a little tired of buying these expensive rebuild kits. Oh well, that's what you get when you buy a 30 year old bike which has been parked for most of its life. 30 years old and 8000 miles on the speedometer. Yikes!!


You shouldn't have to use a C-clamp to put the caliper pistons in either.



Just wet the end of your finger with a little silcone grease and rub it over the piston and o-rings inside the caliper and it should push together easily.



I am willing to bet that you hooked the o-rings inside the calipers and they are ripped when you get the piston back out again.



You should be able to pull the piston out with two fingers if you cleaned the caliper correctly. There can't be anything left in the grooves before you put the o-rings back into them or everything will bind up. A dental pick is the easiest way to clean out the grooves.
 

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Discussion Starter · #11 ·
You shouldn't have to use a C-clamp to put the caliper pistons in either.



Just wet the end of your finger with a little silcone grease and rub it over the piston and o-rings inside the caliper and it should push together easily.



I am willing to bet that you hooked the o-rings inside the calipers and they are ripped when you get the piston back out again.



You should be able to pull the piston out with two fingers if you cleaned the caliper correctly. There can't be anything left in the grooves before you put the o-rings back into them or everything will bind up. A dental pick is the easiest way to clean out the grooves.


I was just going by this. This "How To Rebuild Brakes" link is under quick reference......but I will try to do by hand from now on.



My link
 

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I have used a,"C-Clamp" to push Brake pistons in for years.Never had a problem.Of course you must align them correctly.I polish mine with some fine metal polish or toothpaste.

If as you suspect the callipers have been submerged in water then they my just be too corroded internally.

I would suspect that there are callipers off other Honda models that will fit.If this were a single piston calliper I can tell you that CB400N/CB750 and CB900(Older models of both) will fit so I'm sure Honda will have used the dual ones on other Models.Post in the Customization section as I'm sure some one in there will know.



HTH
 

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I was just going by this. This "How To Rebuild Brakes" link is under quick reference......but I will try to do by hand from now on.



My link


It looks like a very helpful site!



The only thing I saw doing a quick glance is, I disagree with the C-clamp thing. If the pistons don't slide in easily they aren't going to move the way they should once they are in.



Again, an ultrasonic cleaner can save you a lot of work when working on brake parts. It may not remove everything, but it will remove the majority and leave behind clean dirt to remove, which makes the job easier.



One of those cheap cleaners from Harbor freight works great for these small parts. The only objection I have to those units is resetting the timer every 480 seconds.



You can often times find good deals on both Craig's list and EBay for larger units if you are patient. I got a 5.5 gallon unit for only $100. Of course it took several months of looking before I got lucky.



One disadvantage to one that large though ... I have to use a gallon of Simple Green every time I fire it up, which is something to keep in mind if you are looking ... but is sure is nice to be able to put two heads, two pistons and rods and two carbs all at the same time.
 
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