Carb Cleaning Tips?

[Mike_Berkshire]

Hi, I have recently bought a 1976 US import CB550 and 'those that know' have recommended I join this forum; greetings!
My first task on the bike is to strip and rebuild the cruddy, varnish-rich carbs. I have access to an ultrasonic cleaner but Im wondering if that will be sufficient to clean the float needles, jets, emulsion tube etc or will I have to soak the tiny bits in some spray carb cleaner as well? Any advice very welcome. I want to keep the original Keihin brass components if I can, I dont want to replace them unless I have to. Thanks.

[K2-K6]

Welcome to the forum.

The usual trip up on most gummed carbs like these is the primary circuit and it's jets. Nothing but absolute clean will keep you from chasing your tail.

Definitely keep the brass if serviceable, all the rest is just routine with enhanced attention to detail in getting to where you want.

Plenty of support here for any questions.

Sounds like a good project.

[deltarider]

Hello Mike, your bike probably is a CB550K2. The old style carbs on this model are relatively easy to clean. I've never needed an ultrasonic bath for my carbs, but my CB500 never sits for longer than 6 months and I take some precautions. Your carbs - probably numbered 087A - can be cleaned manually. Although ultrasonic is an option, there is a risk you will loose a tiny plastic part (#1 carb) in the process. I will try to find the link.
The brassware in these oldstyle hardly wears. My parts have been in there for over 140.000 km and there's still no indication of wear.
Tip: before you remove the airscrews (in the side of the carbs) turn them fully in (gently!), counting the turns. Write down the position (turns) they were in, for future reference. I'd like to know whether yours has the solid pointed airscrews or the cross drilled open ended ones.
You can find a lot of information concerning your model in the parts list here: https://www.honda4fun.com/dwnload/Part-List/CB550/CB550-K0-K1-K2-Parts-List.pdf 

[Nurse Julie]

Welcome Mike, I'm pleased you joined us. I've just posted your bits 😊😊😊

[Mike_Berkshire]

Thanks for the warm welcome and helpful info everyone and Julie for your patience and knowledge. It would be really helpful to know more about the small plastic part in carb #1 if you can find the link @deltarider; I havent come across that yet. I am mostly following an instructional video on Youtube - https://www.youtube.com/watch?v=JFTOfYl5BSc&t=962s

Great news that these parts clean up well - onwards with the adventure!

[Johnny4428]

Hi Mike, welcome to the forum, agree with above advice. Worth spending time cleaning making sure all these small air and fuel passage ways are clear indeed or you just end up taking them off again. Also take note of jet sizes needle positions etc, you never know who or what is been in there before.

[SteveW]

I use caustic soda on the brass bits. Just a small amount in a cup of water for 10 minutes or so.

Do not use on aluminium.

[deltarider]

Found it: http://forums.sohc4.net/index.php/topic,185851.msg2152800.html#msg2152800 Ultrasonic bathing is no guarantee.
I never needed anything else than carb cleaner and some stranded copper wire. There is no need to separate carbs from the rack ever.
One possible exception is leakage of the O-rings at the T-joints. After 47 years mine still don't leak, but in hibernation I keep my carbs in a natural state which is wet. When carbs have been drained for a long time, O-rings will shrink however. In most cases after readmitting fuel in the lines forsaid O-rings will leak at first but giving it some time, they restore themselves into the original size.

[Mike_Berkshire]

The stripdown is going well but I have a couple of questions I am hoping somebody can answer. Firstly, what are effetive ways of removing an emulsion tube that is stuck in with crud? The internet suggests bashing the slide end with a metal punch or screwdriver to 'tap it out'. Looking at the thin walls and the fact its brass; this seems to be a surefire way of turning it into a small piece of scrap. Secondly, each of the slides seem to have similar graunch marks at the end closest to the emulsifier tube and the burrs catch slightly as the slide is withdrawn from the carb body; see picture. Any thoughts if this needs treatment and if so what? Cheers.

[McCabe-Thiele (Ted)]

To release my Emulsion Tubes it started with soaking the carb in fresh petrol for 48 hours as the sliders were also stuck. I squirted the area with Carb cleaner & Nail Varnish remover before drifting them out.

A few years ago I bought a set of long drifts in various diameters with a flat ends for drifting out bearings. One was just the right diameter to fit over the slightly proud Emulsion tube - a light tap made it flush with the carb body, the next size down just cleared the carb body. It fell out with barely a tap.

Heat might have helped though I did not try it as I'm always afraid of melting alluminium - a hair drier might have helped. I was lucky as I did not mark or distort anything - a plastic drift tip might have been better but I do not have one.

[K2-K6]

If you've a wallpaper stripper or similar, then a steam nozzle can often be an easy way to get gluey carb parts apart.

Looks like someone has already been in there before you with that slide damage, not too bad in reality and likely to clean up with "light" dremmel fettle or by hand with emmery cloth.

[Bryanj]

That damage is using a screwdriver to lever it open

[Mike_Berkshire]

A good quirt of WD40 and a couple of hours later I used a pencil as a drift; tapered end cut blunt and seated onto the top of the tube - came out easily.

I'll use some very fine grit wet and dry on a flat surface to take the burrs off.

[Laverda Dave]

I use clock cleaning fluid on the brassware. I pour some into a jar (you have to dilute it) and leave the brassware to soak for a couple of hours. Once  rinsed I put them into the ultrasonic bath with carb cleaning fluid from Allendale.
I got the tip for clock cleaning fluid from the Repair Shop on TV and after watching an Allan Millyard video where he used it on some Z1 carbs.

[K2-K6]

I use clock cleaning fluid on the brassware. I pour some into a jar (you have to dilute it) and leave the brassware to soak for a couple of hours. Once  rinsed I put them into the ultrasonic bath with carb cleaning fluid from Allendale.
I got the tip for clock cleaning fluid from the Repair Shop on TV and after watching an Allan Millyard video where he used it on some Z1 carbs.

Interesting lateral thinking there Dave, seems appropriate to the materials in the jets themselves.

List of ingredients here

 3. COMPOSITION/INFORMATION ON INGREDIENTS
Component CAS Number Percentage
WATER 7732-18-5 10 - 25
ISOPROPYL ALCOHOL 67-63-0 20 - 25
OLEIC ACID 112-80-1 5 - 10
PINE OIL 8002-09-3 5 - 10
AMMONIUM HYDROXIDE 1336-21-6 30 – 40
The exact concentration of composition has been withheld as a trade secret

Ph listed as 11.5 on msds sheet, for the concentrate.

Camera technical often use "lighter fluid" for old and gummy parts, quite effective too.

The steam suggestion comes from analytical chemical laboratory in which the glass vessels are routinely steamed to remove residue, sometimes "tarring" that's similar to that whichbwe get in carbs etc.

A number of different solutions to try.