Re: New member from the STL. 1981 CB750C

Posted by djpj on
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/New-member-from-the-STL-1981-CB750C-tp4060432p4060561.html

Update

It's been a weekend of failures.

I tried the lemon juice boiling trick and either I didn't get the real lemon juice (said 0% daily amount of vitamin C) or I didn't cook it long enough (30 mins and moving it every 5 min) but it barely did a thing.

So, I polished the valve seat for carbs 1 & 2 with some metal polish and it came out like a mirror. Then I clean up all the float bowls with some carb cleaner. Put it all back together and then the number 1 carb wasn't getting any fuel into the cylinder so I opened the drain and nothing came out. And I noticed 3 & 4 were now overflowing.... I know, I know, I should have polished those seat valves while I had it out.

So I took the carbs back out of the bike and opened up number 1 and it had no fuel and the float was way higher than the other. I guess I got a bunch of carb cleaner on the float needle and the rubber part swelled up so it was blocking the passage. And the passage plug got soaked and just fell apart. I think this is a case of "too much of a good thing". Then the bowl gaskets fell apart.

So I ordered 4 new gaskets, a pack of passage plugs, and a new float needle from vintagecb750.com. Hopefully it gets here soon. Otherwise they are pretty clean, maybe that lemon juice did something after all.

http://imgur.com/OhD72LD 
I added those tubes to the overflow to help me recognize problems more accurately and drain them more cleanly as needed.

While I am waiting on that I decided to flush out the front brake lines. The fluid was black as night. I proceeded to open the bleed valve and squeezed lever and I got a little bit out but right before the master cylinder was drained the lever went rock solid. I poured the remainder of the fluid out of the cylinder and the bottom was filled with sediment. Couldn't even make out the holes in the bottom. Spent 20 minutes working on it and it looked like this
http://imgur.com/Z8ez801 

I pulled the lever and cylinder off the bike and cleaned it all and got some fluid flowing through it but the main brake line is clogged solid. I can't even get brake cleaner through the line and I'm not about to ram a wire through it all.

So I'm left without front brakes and no carbs... Better to find out now than on the road I guess......

PJ