Topic: Honda CB 500 Four carburettor drawings.

[FoxDK]

Hallo,

Do any of You know, where I can find a large overview drawing of the inside of my carburetors?

It is for a 1977 Honda CB 500 Four. Frame number: CB5002092696

The carburettors (Keihin) is marked with the number: 649A

Regards Frederik, Denmark

[dave500]

ive never seen a clear one?plenty of carb rebuild threads here with good photos if you search.

[Deltarider]

Drawings are in almost all manuals, but the ones I've seen are so and so.
What would you like to know, Frederik?

[wowbagger]

Yup,

the only ones I've seen are the exploded view parts fiche like this:
http://www.cmsnl.com/honda-cb550k3-four-1977-usa_model1015/partslist/E++1701.html#results

[Muckinfuss]

Nice pre-unit BSA!

[strynboen]

the problem are the emusions tubes...they falles dovn aut. .when taking/pull the main jet(dyse)...must there be a o ring on emu tubes)....?

mine 550 are the new type...kaburators..have not worked on the older types

have heped frederik on the 500
..have tested oil pressure vith a extern gauge..(he had a defekt pressure indikator)..but there vas some kaburator problems..stock flots...o ring vas been big..not fuel resistiens...and this loose parts falling aut of the kaburator..and some ignision problems..coils are a bad fabrikant...

but the rest are fine..saund engine...fine exhausts. elektric good( and paint just perfekt)..a nice machine..just need a small opdate to run perfekt

[Deltarider]

Strynboen, if the emulsion tubes (or needle jets in Honda speak) come down after you've removed the main jets, that's fine and not a problem at all. There's certainly no O-ring in there. If the needle jets don't come down rightaway however, here is what to do.

After removing the main jets
Twist the throttle at least halfway in order to raise the needles and then insert from below a match or wooden toothpick into the needle jets. When that is snug in the needle jet, cant or turn the wooden toothpick a mm or so and you can wiggle the emulsion tube out easily.
Some WD-40 at forehand can help.
Essential in this procedure is that you open the throttle to raise the needles.
Has always worked for me, but most of the times they just dropped after the main jets were removed. Very simple. Keep the parts separate in containers or boxes 1,2,3 and 4 and make sure you assemble them correctly and not upside down. Inspect O-rings around main jets if they still seal well. These carbs are so easy to work on. Don't separate them from the rack. For maintenance removing the floatbowls is enough, the rest is to fill pages in manuals. Piece of cake.

[strynboen]

fine...ve just take the kabs off the bike...klean all and put some new o rings inn...

i vas thinking...can ve cut threds in the emu tubes..to pull them dovn aut(if they are stock) korrodet

[strynboen]

ve still have some problems running lean...it runs best at half choker..and miss1 cilender firing...frederik have byed nev ignision plate.(.burned knickers..) and the coils vill be thanged...

but the main problem ate fuel starvasion..so the karbs must be total kleaned..and tank and filter...so it not vill fill dirt back inn

[flybox1]

you can also take the slides out and press the emulsion tubes out/down from the top. 
use a wood dowel.

[strynboen]

yes  ...but ve trying to make as simpel as poss..and not pull anything vho not are  to be kleaned..or can be  hiding dirt..

[Deltarider]

I would also clean the slow jets and all the passages. Spray carb or brake cleaner and check if all 4 exits are free. In the 649A setup, the slow jets play a role not only at idle. Clean them, using copper wire maybe after you've soaked them in carb cleaner. I do not recommend guitar strings.
What passages do you have.
The opening in the carb mouth. See pic.
The slow jet.
The airscrew (hollow!)
The tiny little hole right in front of the carbs slide engine side.
DO NOT USE FORCE. DO NOT USE ANY MATERIAL THAT IS HARDER and you will not have to replace any parts. They rarely wear if at all.

[Deltarider]

you can also take the slides out and press the emulsion tubes out/down from the top. 
use a wood dowel.

(sigh) You've must have been reading this forum a lot.
I repeat. The removal of the float bowls is enough for maintenance. Do NOT remove the top lid, do NOT remove the slides. Not necessary at all.

[strynboen]

saunds as a plan...
vaccum syncro...is it the big brass schrevs...not some small schrevs inside undet the cap,,, as the never type...think not i can use my 550 kombi  tool for inside adjusting

[Deltarider]

And this what the air screw looks like. It is cross drilled, has a hole in it's tip, goes in there with a spring and has NO O-ring (unlike the K3 that needs a tiny O-ring). 

[Deltarider]

And don't be tempted to change jets and needle positions. You have an original bike with four exhausts and I presume standard airbox. LEAVE IT LIKE THAT and you'll be happy. What's is written in manuals is academic and is there to fill pages.

[strynboen]

ve vill not thange anything..the risk the "new" parts are bad tolerence are too big...flots are fine gas valvets cloce fine..no overflovs...so no need for thange parts..only the o rings are bad..
think honda did it the best vay...so no need for" better then honda" parts...

[Deltarider]

saunds as a plan...
vaccum syncro...is it the big brass schrevs...not some small schrevs inside undet the cap,,, as the never type...think not i can use my 550 kombi  tool for inside adjusting

First of all: what is it that tells you need to sync?
Syncing is epidemic in this forum, as is float tang bending as is separating carbs. You will not find this in the German, French and other SOHC fora, not in the frequency yoú find it here.
If you must sync, it is done differently from the K3 models and you have to be at the little screws that are shown in fig. 7 on page 8 of the genuine Honda Shop Manual. Do you have that manual?

[Deltarider]

ve vill not thange anything..the risk the "new" parts are bad tolerence are too big...flots are fine gas valvets cloce fine..no overflovs...so no need for thange parts..only the o rings are bad..
think honda did it the best vay...so no need for" better then honda" parts...

Strynboen, you are a pro! Applause!

[strynboen]

i have only the k3..but frederik komes vith the right book..


yes vaccum cyncro are the last step

..it must run nearly as perfekt in a simpel adjust.

...cyncro just do it perfekt...it are the last 5% to make it perfekt

ve must have all bugs killed..and have it run for some time before the last step..who are the vaccum adjust..

but it are alvays the work worth..it smmoths it aut,,and take all rattel aut of the engine...seving machine must be the word. i think.my english are hell

[Deltarider]

Data offered in this site is often corrupted.
P8 is missing in the manual 500/550 in this site.

You'll find p 8 in the manual over at our Italian friends who offer the best.

http://www.honda4fun.com/pdf_man_officina/pdf_manuali/CB500-550/CB500-550-K_01.pdf

You're English is maybe not the queens English but I like it. Don't you hate them snotty stiff upper lips? Bwah!

[FoxDK]

Thank You all for your answers It is appreciated!

And a special thanks to Lars (Strynboen) for his kind help with my old Honda. Hopefully we will get it running well soon. We found out, that we were almost neighbors.

I have printet a large version of the carburettor drawing (A4 size) and the quality is OK. Thank You wowbagger.

Best regards,

Frederik