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Discussion Starter · #1 ·
I have decided hell or high water this bike will run again.

It is not rational but there it is.

So The front brake reservoir was bone dry when I got it. The previous owner told me (with a straight face) the front brake CABLE was broken and would need to be replaced. I looked at the master cylinder and thought OOOOOHHHH-KKKAAAAYYY but kept it to myself.

So I put fluid in and got almost no pressure when I tried to bleed it. I figured the master was filled with... well..crud. I pulled it and was not surprised.

I had to drive the piston out with a brass punch after pulling the spring clip. The washer had rusted to the cylinder. I figured I would clean it up even thought I pretty much figured it was scrap.



CLR and one of Larry's sonic cleaners - wonderful toy, did amazing things. The bore still had some residual uglyness when I looked down it.

I know there are hones for this but I picked up an extra 410 shotgun bore cleaning "Wool Blend Mops". I cut a cleaning rod to about 6 inches then put it in my variable speed drill. A touch of toothpaste and few seconds in the bore and it looks like a mirror.



I am not sure if there is anything wrong with this approach but it sure looks great.



Thought I would share.

I am going to have to put a rebuild kit in it because the washer, spring clip, and dust boot are all messed up. The piston looks good the spring and other rubber seal all look good. A shame to spend $40 for a kit but if your in there do it right.

Anyway I will put a stainless steel line on it and redo the caliper next.

Let me know if there is a problem with using toothpaste and a 410 shotgun mop.
 

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I couldn't see toothpaste and a 410 mop being to bad for it but I have been wrong before.



I know that a big problem with these master cylinders is the return hole getting plugged up with gunk and causing the brakes to drag and stick or something like that. Is it better to replace them with a new master cylinder or just rebuild the existing one? How long will the master cylinder stay unplugged?



I know their was a thread about someone crashing because of the master cylinder locking up. (It was a while ago, I can't remember who it was)
 

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I think 9 out of 10 of us always agree on a thread about master cylinders that the most prudent thing is to simply replace the old one.....buying a new one is sometimes not anymore money than a rebuild kit and a nice one is only a little bit more.



Peace of mind
 

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I think 9 out of 10 of us always agree on a thread about master cylinders that the most prudent thing is to simply replace the old one.....buying a new one is sometimes not anymore money than a rebuild kit and a nice one is only a little bit more.



Peace of mind
Couldn't agree more. If the MC was in pretty bad shape, I wouldn't trust it without a rebuild including new piston, seals, spring and honing the bore. Often, replacement is cheaper.
 

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Discussion Starter · #5 ·
Rick

I understand. Any suggestions on where to find one that is reasonable cost and will work for my 78 CX500?

There was a thread here earlier about a chinese made one that was cheap but I never saw a resolution to if it worked or not. Besides I am not sure I really want the cheapest master cylinder I can find. Even if it worked well I would still feel like it was the cheapest master cylinder around.

Thanks!
 

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HoWDy c0wB0y!1! (TonyR)



Check this ebay seller out:

http://motors.shop.ebay.com/usa-mot...kw=&_osacat=0&bkBtn=&_trksid=p3911.m270.l1313

Scroll through those master cylinders and find one that fits your bike...most will. LOTS of us have bought these, they rule. PLEASE NOTE that he does sell master cylinders with angled reservoirs that fit our custom style handlebars perfectly, if those are the handlebars you are using. IGNORE what type of bike it fits, just find one you like and buy it. Make sure it has the right banjo bolt, but most or all should.



If you really want a rebuild kit search "cx500 master cylinder" on ebay and a bunch of kits come up.



Also while you're at it, you better look long and hard at that brake hose. If it's OEM rubber it's probably time to replace it. You can get very nice stainless steel coated brakelines from this guy:

http://www.jdaent.com/



Lastly I would also pull the caliper off and get the piston out. Clean out all the crap and replace the seal, it's only a few bucks. I know it sucks when 1 thing leads to another, but if you put a new product on a crummy brake system you're just waiting for the next thing to go wrong.
 

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Discussion Starter · #7 ·
Morrow,

Thanks for the link! I already planned to buy a stainless hose. I am going to pull the caliper tonight.

I am also going to look at changing the fork oil to 20W. I want this thing to stop when I ask it to.

It is a project bike and I have never ridden it. If I do not like it I want the next person to buy it and be able to have confidence. If I do like it I want it right.

 
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