Brake and fuel problems

If it's broken or just needs tweaked

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new81cb650c
Posts: 4
Joined: Sun Aug 20, 2006 5:53 pm
Location: East Central Iowa

Brake and fuel problems

Postby new81cb650c » Sun Aug 20, 2006 6:26 pm

I am the second owner of an 81 CB650C which had 833 miles on it when I bought it. The carbs and air box were out and no air filter. Front master cylinder was also non-operational. This bike is my first and has sat for the last ten years inside a garage. To get to my problem, I have got this back together and seems to run good down the road but leaks fuel out the carbs. Will alternate in between carbs not always leaking on the same ones. I have replaced the float bowl gaskets and have had the floats and float needles out many times. The last time I found rust deposits in the bowls, and have since found the strainer on the petcock has dried up. I put in an in line filter until the strainer arrived which slowed down the leaking. The strainer arrived and was installed and the problem is back to normal(leaking). Now I thought it was related to rust deris not allowing the float needle not to seat and overfilling the bowls. Right! But do I need to take apart the carbs and clean all of the seats?

Second question is my front calipers will occasionally stick when I first get on. After a little ride it becomes free and no problem. Here is possibly some better information about the brakes. I rebuilt the master cylinder and reinstalled. I tried to bleed the brakes just like a auto, pump the brake- open the bleeder, repeat until no air. But I got no fluid or air, tried to gravity feed but got nothing again. When all was said and done I had to run some wire down the hoses to free build up of bad fluid and chased it with air. I then reattached everything and got it all bled. Now the caliper will ocasionally stick. Today for example I didn't even get a half mile and it kept getting worse. I ended up cracking the bleeder screw and relieved pressure and it worked fine the rest on the ride.

I've been working with cars the last ten years and even with the clymer book I can't figure out what is wrong. Any help is appreciated.

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Chris
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Joined: Thu May 04, 2006 12:51 am
Location: New York, USA

Postby Chris » Sun Aug 20, 2006 9:44 pm

Welcome. Sorry I don't have any advice for you, but just wanted to say welcome to the forum.
1980 CB650c

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Volker_P
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Location: southern Germany

Re: Brake and fuel problems

Postby Volker_P » Mon Aug 21, 2006 1:35 am

Welcome to the forum.
I think you blew a lot of additional mud down into your front brake calipers (some of the mud of the old master cylinder obviously was already there) so it is time to open and clean them before you scratch the piston and caliper surface and the whole thing even starts leaking. Don't expect it to get better, just do what you have to do. Don't forget to lubricate the caliper's gliding bolts (That's something everyone should do from time to time, no opening of the hydraulic circuit is required). If it still sticks after that, then maybe you mixed up some parts during your master cylinder rebuild.
You can clean the carb seats without taking the carbs off if you have a right-angled screwdriver to get off the floater bowls. You can even do that somewhere at a french parking lot at hot engine while a bunch of german bus tourists is standing around you watching you burning your fingers, but this is a different story. :lol:

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Ibsen
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Postby Ibsen » Mon Aug 21, 2006 2:36 am

Welcome to the forum. :D

Another thing to check and clean on the calipers are the area on the pistons between the dust seal and the edge of the cylinder.
And if the lever is still soft after bleeding the brakes, open the lid on the reservoir and then pull the brake lever and strap it to the handlebar over night. That will remove the last remains of air bubbles in the system, allowing them to rise and vent out through the master cylinder.

cb650
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Postby cb650 » Fri Aug 25, 2006 9:23 pm

Clean the tank out also!



Terry


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