Topic: 76 cb550 carbs

[metalhead0283]

so i picked up a 76 cb550f bike has 4400 original miles...it has been sitting for 19 years n of course it needs some work...traded some stuff i had no money in so no money invested yet...well 3 out the 4 carbs r wasted...not fixable...the post where the push in jet goes is rotted off basically...but 1 mint carb out of 4 is um well #$%*ty...what other year cb bikes carbs will work with this? i understand jetting will need 2 b done...if i can find a stock set for the 550 that needs a rebuild its fine but there aint much on ebay for the 550...also got no spark but i can figure that out fine..i have worked on xs650s so i know lil bit bout lousy wiring..lol..gonna cafe it

[dave500]

got any photos?

[metalhead0283]

of carbs or bike? either way i will get some pics up tomorrow

[dave500]

sounds you have the "type one carbs"if the jets are push in,in that case dont buy the later "pd"type carbs,most any type ones from a 500/550 will run fine on your bike without any alterations,be aware that used ones have been tampered with no doubt so check the jets havent been changed or drilled or mismatched etc.

[TwoTired]

The only direct replacement carbs for the F model Cb550 are 069A series.  Are you certain it is an F model?  (The VIN must have and F in numbers.)
However, if the air filter and a exhaust are modified, the 069A set up will no longer be valid.
The carb bodies are the same for 069A 75-77 Cb550F, 087a 76 Cb550K, 022a 74-75 CB550k, 627B 71-73 CB500.


If you change the intake manifolds, carb couplers fore and aft, and the air box from the donor, PD carbs for the 77-78 Cb550K can also be used (with jetting changes).

[mono]

since this is already a carb thread for a pertinent 550, i'll just ask here:

i'm cleaning/rebuilding my carbs right now, and one of my floats seems heavier than the others.  i.e., when i have them upside down and they are resting on the springloaded needle, one is weighing down the spring.   3 of them can bounce around like Baywatch lifeguards, but carb #3's floats just bottom out.

-- they are all bone dry.
-- i measured them with a caliper and they are all the same dimensions.
-- the arms to the floats are not bent.

can i remove material from the saggy one to let it travel like the rest or will that not matter?  i'm guessing if it's a matter of foam density, then removing material to make it weigh less would not matter.

thanks, fellers.

[TwoTired]

Does the "heavy float" stay heavy if you temporarily swap the float needles?  Or, does a new float become heavy with the needle move?

Have you actually weighed the floats?  I wouldn't change their mass without doing that.

Don't modify the wrong thing.  Could be the spring pins in 3 valves are sticky for extra support, or a spring pin in one may have half collapsed (and stuck) leaving only half of it to provide rebound pressure.

Assuming the problem moves around with the needle, bathe/soak them all in carb cleaner (keeping their mated seat relationship).  And exercise the pins to help clear any glue they've absorbed.

Cheers,

[metalhead0283]

thanx so far for the help!!! ill post some pics tomorrow

[metalhead0283]

also any here done kick start only? i wanna take out what isnt needed an clean it up a lil bit

[c(b)hris]

my 75 550 is kick only.  my right hand controls were trashed and i removed them.

[Flying J]

Why not keep the starter? The bike looks the same with or without it. The weight difference will not be noticeable. You want to loose weight get rid of the front brake, that thing is heavy. 

[mono]

Does the "heavy float" stay heavy if you temporarily swap the float needles?  Or, does a new float become heavy with the needle move?

Have you actually weighed the floats?  I wouldn't change their mass without doing that.

Thanks - good points.  I'll switch them around/weigh them.  they are brand new parts, though.

[Duanob]

Does the "heavy float" stay heavy if you temporarily swap the float needles?  Or, does a new float become heavy with the needle move?

Have you actually weighed the floats?  I wouldn't change their mass without doing that.

Thanks - good points.  I'll switch them around/weigh them.  they are brand new parts, though.

Another simple test is to float them in either a tray of water or gasoline (be careful!) and see if the number 3 isn't gas-logged. If it is you will need a new one. Even if you can dry it out it will soak it up again.

[mono]

Another simple test is to float them in either a tray of water or gasoline (be careful!) and see if the number 3 isn't gas-logged. If it is you will need a new one. Even if you can dry it out it will soak it up again.

thanks - i'll give that a shot!

[metalhead0283]

well found a set of cb500 carbs that will work on ebay...even better they r in the my state so gonna ride up on my triumph friday n grab um...next question is what size jets do i use? i am gonna b putting pod filters on n a free flowing exhaust...also not doing kick start only cuz i decided to make some custom polished aluminum side covers so the electrics will b hidden

[Flying J]

for stock jetting look here.
http://www.motorcycleproject.com/motorcycle/text/specs.html

If your going to run pods. Just slap a larger main in it. Youll never get it to run perfect with pods. So buy a few different size mains. Do some plug chops till you get tired of doing it and then youll feel  like its good enough. On the bright side you have never run it with the stock air box so youll never now how smooth or fast it could run.

[mono]

Does the "heavy float" stay heavy if you temporarily swap the float needles?  Or, does a new float become heavy with the needle move?

UPDATE and SOLUTION:  this is something to look out for if you order a rebuilt kit -- one of my 4 replacement needles had a weak spring it in!  moved the floats all around and every float would sink on this one.  cleaned up an old needle of the same size and it works A-OK.

[Deltarider]

http://www.motorcycleproject.com/motorcycle/text/specs.html

That scheme is corrupt and I've posted this more than once. One of the blessings of internet: mistakes will remain there forever, unless somebody corrects them.
For instance: has any of you seen a 500F with 022A carbs? Then why does nobody ever correct it? 1¹/₂ - 2 turns out, JN4, 4? where does that come from?
Tip: ban scheme's that are corrupt and incomplete.
I mean: where's the 627B (carbs 500), the 649A (id), the 087A (550K), where is the 500K3?. Why not for once and for all make a proper scheme? I'm willing to help.

[metalhead0283]

running pods n diff exhaust...thought you change more then just the main jet...n what size jets anyways?

[Flying J]

Yes you should also move the needle and possibly change the pilot jet.
As for your second question, there is no definite answer. You just need to start with something and see how it runs. Do a plug chop to see if you have the right size main. Then move on to the needle and then the pilot.

[Flying J]

http://www.motorcycleproject.com/motorcycle/text/specs.html

That scheme is corrupt and I've posted this more than once. One of the blessings of internet: mistakes will remain there forever, unless somebody corrects them.
For instance: has any of you seen a 500F with 022A carbs? Then why does nobody ever correct it? 1¹/₂ - 2 turns out, JN4, 4? where does that come from?
Tip: ban scheme's that are corrupt and incomplete.
I mean: where's the 627B (carbs 500), the 649A (id), the 087A (550K), where is the 500K3?. Why not for once and for all make a proper scheme? I'm willing to help.

I have never owned a 500 so i didn't know any of it is wrong. It has been helpful for the 550's and 750's i have owned. Maybe the moderator could add to the post alerting people of the errors on the faq page.

[TwoTired]

http://www.motorcycleproject.com/motorcycle/text/specs.html

I have never owned a 500 so i didn't know any of it is wrong. It has been helpful for the 550's and 750's i have owned. Maybe the moderator could add to the post alerting people of the errors on the faq page.

The site's owner is Mike Nixon.  I like Mike.  He used to post here on the forum a while back.
Years ago I sent him corrections for the chart and had a dialog for explaining the corrections.  He said thanks. 
...And, the chart remains unchanged from when first posted.

[metalhead0283]

Yes you should also move the needle and possibly change the pilot jet.
As for your second question, there is no definite answer. You just need to start with something and see how it runs. Do a plug chop to see if you have the right size main. Then move on to the needle and then the pilot.

yeah thanx...what place u guys buy ur jets?

[Flying J]

jets r us

[metalhead0283]

so im ready to order jets..stock is 98 for the main n pilot jet is 38..how many sizes do i go up on the main b4 changing the pilot jet? i gotta get it close as i can first time im not in the mood to buy $100 worth of jets right now...say i go 105 on main rule of thumb what should the pilot jet b an setting the slide needle