Topic: Re: CB550 Carb Rebuild... Man, what a great resource

[chaloots]

Just want to say thanks to everyone who contributes to this great site. 

Everything from detailed DIY to real working experience tips and more, have made working on the SOHC/4 so much fun, even for a guy like me with zero SOHC/4 experience and big fat thumbs that always seem to get in the way... if you know what I mean.

Check out the photo for just a couple of examples of real useful info from this forum that was so helpful to me in rebuilding my CB550 carbs this weekend.
(hope the photo loads...) 

(Ex: the float level gauge, and the Scotch tape tip, to hold the float bowl gaskets in place).  So simple but so good.  Man, what a great resource!

Thanks again guys, and hope that I'll be able to contribute something to the forum in the future, as well.

Chuck

[dave500]

good work on your part!

[chaloots]

Thanks, it's been fun... But now a little frustrating. 

Put carbs back on last night, hooked up everything. Opened up the petcock and...
Yep you guessed it... leaking gas out the overflow tubes big time. 

Had installed new float valves and seats during rebuild.  Have been careful and  meticulous with this carb rebuild.  Even so, something must be hanging up inside.

Where to go with this now?    Not looking forward to removing the carbs again.

[ADW]

If you used Keyster rebuild kits for the carbs, many report the fuel valves in those are way too stiff, causing the float not to shut off the fuel flow properly. I'm no expert, and I didn't stay at a Holiday Inn Express last night, but you might try reinstalling your original fuel valves and seats and see what happens. FYI if you used the jet needles from the Keyster kits those also are supposed to be PoS parts as well.

[grcamna2]

Have you tried lightly tapping on each(whichever one is leaking)float bowl ? sometimes the float will slightly hang up until it seats initially.Does your fuel source/tank have clean fuel flowing into the carbs ? Did you set the floats as per the factory spec with a good float level gauge ? chaloots..confirm a few of these things before you pull your carbs back off(you may have to anyway)and if you can later maybe take a few pictures of the inside of the carbs...if you need to disassemble them again..... All the Best to you !  +1 w/ what ADW says, nothing like Original Honda carburetor parts , even if they are a little used or dirty;post a few close up pics so we can see the condition of your floats and original float valves when they're all cleaned up.The float "tang",the little brass metal piece of the float that makes contact w/ the float needle valve should not have any little hole worn into it because the float will stick and hang up on that indentation.

[bryanj]

Also you need to check carefully the brass tubes inside the float bowls as with age and cold they do crack letting gas leak out no matter what the float valve does

[grcamna2]

Also you need to check carefully the brass tubes inside the float bowls as with age and cold they do crack letting gas leak out no matter what the float valve does

+1 w/ bryanj sometimes those little brass overflow tubes can have the tiniest little cracks in them you could barely see them unless you use a little scotchbrite to polish them a bit.

[CoachDoc]

+2 on checking for cracks in the overflo tubes and going back to the original float valve hardware. That's how I did my '74 550 carb rebuild. New rubber parts, but a meticulous cleaning of the original jets and needles. Carbs 100% now.

[chaloots]

Funny how working for a living can get in the way of doing the important things in life!
Will get back into the garage today and followup on the the good feedback.

Have a few pics of the carb bits and float bowls before cleaning. Will post up later.

[Bankerdanny]

Unless your bike has very high mileage I would re-use the original float needle and seat and just replace the o-ring.

+3 from me on the cracked overflow tube. It happened to me when I refreshed the carbs on my '77 even though it only had 7k miles on it (but had been sitting with gas in it for 28 years before I bought it).

It is possible to remove the float bowls with the carbs on the bike. A medium length #2 philips bit is just the right size to fit between the carb and the case and a 1/4" wrench fits to turn it. With the carbs on and the bowls off, you can gently (and I mean gently) push the float up and hold it while you turn on the tap and see if fuel comes out.

[chaloots]

Well was able to get back to the carb issues... and based on the feedback, removed the carbs from the 550 again.

My plan is to rig up something on the workbench (as others on the forum have done) to hold the carbs, provide a fuel source and see if I can sort this out in my nice warm basement.  Will try to determine if the overflow tubes are OK, and otherwise set the float float levels.  Also will clean up and install the original float needles and seats, and will remove the new Keyster parts. Will need to get new o-rings.

To answer some of the questions ...
    - Yes... tapped on the float bowls to see if the floats were hanging up but this didn't help.
    - The tank is rust-free and clean and the fuel is fresh and clean.
    - I carefully set the floats with a float gauge I made using an idea from the forum tips.
    - Noticed that the "brass tangs" on  the floats were indeed a little pitted.  Will plan to dress them up.

I Bought the 1974 CB550 from the original owner with less than 12000 original miles.  It had been stored in the back of his garage since he stopped riding in 1982!  The bike was covered with 37+ years of dust and grime but no rust. The garage was dry. The fuel tank was full to the brim with gas from 1982 and surprisingly didn't have that old varnish smell.  Brought the bike home cleaned it up a bit and it sat in my garage for a year.  I began to work on it again this past November.

When I opened up the carbs the bowls were full of gunk and hardened varnish. Also there was some white powder on some of the bits as well.  See attached pics.

So far, I have cleaned and polished everything, and the bike look great.  Changed the fluids, new filters, bled the brakes, and after squirting a little lite oil in each plug hole, cranked it over a bit.  So now I'm anxious to get the carbs back on and fire it up. 

[mainstage]

Did you every figure out the problem?

[flybox1]

wow, this is an old thread