Topic: Carb cleaning

[scunny]

sure looks better than my carbs, any issues with doing this, would having a G&T at the same time help?

[TwoTired]

Acids will, of course remove some metal, too.

I was under the impression that the carbs were flash coated with some sort of preservative coating.  Cad plate perhaps? Would seem an acid bath could remove this.  They are clean now, but, will it last as the surfaces oxidize?

Also, the air jets are drilled into the body.  The orifice size could be altered with an acid bath, depending, of course, on the duration and strength of the acid being used.  I don't know if it will change mixtures enough to effect other jetting, as I've never tried acid dipping carb bodies.

I think I'll stick to the carb dip, though.

Best of luck!

[Jonesy]

It's an interesting contrast in cleaners. The lemon juice is acidic (as TwoTired pointed out) while most carb soaking liquids are basic. I'm wondering what effect bases have on metals? I've seen some carb cleaners strip Zinc Chromate coating off of some carb parts...

[puppytrax]

Adventures in carb cleaning

Gunk versus Yamaha carb cleaner

Well, I've read the threads here (and the FAQ) on how and what, so I decided to try cleaning some carbs myself. My 72 CB500 came with several sets of carbs, and through bar-buddies and my friends' old projects, I ended up with two more CB550 parts bikes, with more sets of carbs. Plus I bought a set from a SOHC4 member. All sets were pretty dirty; actual chunks of corroded aluminum falling off the main jet holder in some.

For the first set of carbs, I used the Gunk Carb Cleaner [part # CC3K] from an in-town Advance Auto. About $10USD for a gallon pail about 3/4 full of solution; includes an insertable half-qt perforated parts tin with handle. I had to separate the carbs from the backing plate as I could not find a watertight bread baking pan to put the whole rack in, so I just dunked them in the pail, with welding rod "S"-hooks attached so I could pull the parts out.

I let the individual carbs, bowls and cover removed, soak for about 16 hours. Worked pretty well. Gunk leaves a greasy-feeling surface behind when it is done. But nice and clean. Requires a bit of scrubbing with a fine brass wire brush and a 2" paint brush with half the bristles cut off to get rid of extreme dirt/corrosion which the Gunk had loosened up.

I had to go fairly far afield to find some Yamaha carb cleaner. A Kawasaki/KTM dealer in another town had it (he also sells Yamaha jetskis; but not cycles...go figure). I got two one-quart bottles; ~$10USD a bottle. Plastic bottles.

For the next set of carbs, I bought an empty gallon pail from Ace Hardware, along with some 22 gauge wire (for hanging parts - this stuff does a job on exposed skin). I also poked some holes in a tunafish can to keep submerged parts separated. Next I mixed the Yamaha stuff 1:1 with water (as advised in another thread here), and put it in the gallon pail. (The pail came with a nice sealable metal lid; unlike 3# coffee tins - they have plastic lids). Not having a hotplate (or wife), I chose the kitchen stove to heat my cleaner. I took a frying pan and put about 1 1/2" of water in it, and brought it to a boil, and set the pail of cleaner in the water. Checking constantly with a Centigrade thermometer, I kept the water boiling, replenishing as necessary (about every 30 minutes) to keep water level constant. I let it boil for about three hours. [Warning: if you do this indoors, it will stink, and you *will* have a sore throat]. I kept exhaust fans on and windows open. The temp of the Yamaha solution never rose above 82*C, and only took 30 minutes to reach that temp. The Yamaha solution does boil off however, so I kept replenishing the water level in the Yamaha solution as well as the frying pan. (I'm not sure if it was the water or the Yamaha stuff that was boiling off).

The carbs came out nice and clean, but after drying, they all had a white "ash" on their surfaces. It will wipe/scrub off, but is rather puzzling.

All carb parts, whether Gunk or Yamaha treated, were washed off in soapy water, rinsed, then blown dry. I wear rubber gloves when handling caustic substances.

The final treatment was to boil another set of carbs (lots of these old dirty junk Honda carbs <sigh>) in the straight Gunk solution for three hours, in the water/frying pan. Actually, I let the first one soak overnight in Gunk unheated, then heated it in the morning for three hours. Same process of replacing boiled-off water in the pan every 30 minutes, keeping it at a boil. Solution constant at 82*C. I left the pail lid lying on top of the pail, not sealed, just sitting on top of the wire hangers. Keeps most of the condensation in.

My conclusion is that for the best cleaning, boil the carbs. Both Gunk and Yamaha seem to be equally good at it, with the above mentioned greasy/ashy surface differences. Additionally, the Gunk is not as noxious or irritating as the Yamaha. And it costs about half as much for approximately equal amount of solution. Both can be reused, but be sure to seal the pails for storage. The Yamaha stuff evaporates rather quickly. It also rusts the pails it is used in.

The Gunk is advertised as being environmentally friendly as well.

I'm going to keep my eyes open for a hotplate at garage sales, as well as a larger pan/pot for the boiling water. I'm not sure why the solution never gets above 82*C when the water is boiling...maybe the heat radiates away from the exposed areas of the pail??? And I certainly won't be boiling Yamaha cleaner in the house anymore...coff, coff...A table off the back porch is the approved location now.

That concludes this exercise.


Some off-topic notes:

- Gunk Carb Cleaner - part # CC3K - at Advance Auto -

http://www.partsamerica.com/ProductList.aspx?mfrpartnumber=CC3K

- Yamaha Carb Cleaner part # ACC-CARBC-LE-QT -

(available from pretty much any Yamaha dealer)

- For ~$2.50, you can get a 6"/150mm pocket scale/square with a sliding "T" clip at Sears or any good hardware store for setting the float height. The CB500 calls for 22mm. Works good. I followed the instructions for the 750 carb Rebuild at SALO.

- Step-by-step carb cleaning/rebuilding (for 750 carbs) -

http://www.salocal.com/sohc/tech/carb/carb.htm

- NAPA has the o-rings for the "T" fitting between carbs (as noted in another thread here), part # 727-2605, available in box of 10.

- I used the Keysler carb kits; these are junk. I ended up using only the top gasket and the bowl o-ring. The bowl o-ring had to be stretched a bit, and held in the groove with Vaseline so it could be installed.

- Harbor Freight has a Metric o-ring assortment for ~$10USD that has just about every other o-ring you will need, including manifold o-rings. Part # 91512

- Sears has the 6mm and 8mm wrenchs you will need for the choke adjusters and sync-nuts. Or you can buy the "Open End Standard Ignition Wrench Set" part # 944778; inch-pattern, but "close enough".

[superchode]

good info, thanks for laying all that out.

[Lumbee]

...I still have to throw my hat down for Chem Dip...its still been good enough for me not to try the Yami cleaner that I hear so much about...

[Boomologist]

Safety First!
You mentioned a sore throat and nasty smell. That's from the toxic fumes. 
These fumes can cause great harm to your innards. Think lung cancer, brain tumor, heart failure.....
Secondly, those fumes are most likely flammable, if not explosive! The label on the can should say if it is flammable.
When I have the need to heat some nasty substance I use a Colman camp stove outside and I always stay up wind of it with a charged garden hose close by.
Please be careful. I hate visiting people in the hospital and flowers are too expensive to send.
You're lucky to be alive.

[Lumbee]

You're lucky to be alive.

Boom, u'r such a drama queen!!!   

...hes right about the fumes though...get u'r self that hot plate you were talk'n about and boil that stuff outside...

[Boomologist]

>>>Boom, u'r such a drama queen!!!   <<<
I spent 21 years with a fire department and had the privilege of seeing first hand some of the things people do to themselves.

[puppytrax]

You're lucky to be alive.

So my doctors tell me... 

[HondaMan]

This is for CB750, but roughly applies to any slide-type carb.

You already know how to "clean" the carbs normally: remove the jets and spray Brake Cleaner or Carb Cleaner through the holes until they come out clean. This usually works. Some of you are soaking the whole disassembled bodies for days to get the last passage clean: this will speed up that process. After all, mechanics only get paid a fixed amount to "clean carbs"...   

We have all suffered through a (finally gone) period of MTBE-laced gasoline, which attacks the metal of these carbs. The result is a fine white powder (corrosion, actually) that migrates everywhere. If it is allowed to thoroughly dry (like 2 years or so), it hardens inside the passages and narrows (or blocks) them. This alters the mixture properties of the passages.

I was sorely reminded of this when I recently fired up my long-sitting 750, post rebuild. The Emulsifier Air Bleed passages in 3 of the carbs acted like they were blocked (black sparkplugs), but they would pass Brake Cleaner through them. This implied (correctly) that they were PARTIALLY blocked, which is hard to clean. This is a very common problem on bikes that have been sitting long or are ridden infrequently after being fueled with MTBE gas.

The following few pix show how to clean this problem. The first one shows the entry to this passage: it's a little brass jet in the air horn. The second pix shows the passage's direction, and how long the wire has to reach inside to get all the way to the Needle Jet in the center of the carb. The third pix, if you look real carefully, shows the wire up against the side of the Needle Jet, having pushed its way fully through. Since there is a Z-shaped dogleg at the beginning of this passage, use a wire that will bend, not a stiff piano wire. Push, pull, push again: the wire will progress and the crud will break up and work its way to the edges of the Needle Jet, where it can then be flushed away. Be patient and straighten the wire several times, trying again until you can look down into the Main Jet Holder's hole and see the tip of the wire bumping into the Needle Jet's side. You'll be able to feel it opening up the passage.

[HondaMan]

Here's the passage length and route.

[HondaMan]

Here's the wire at the Needle Jet. The wire has been inserted the full length of 1.515" from the Air Horn end.

[HondaMan]

Here's a final note about this passage: this one is the "timing" passage for the start of the Midrange mix. You can make the Midrange start earlier by shrinking the brass hole at the Air Horn or you can make it start later (after 1/8 throttle) by opening up the hole. Make these changes in .002" increments to smooth it to your taste: opening it up about .010" bigger will make the midrange start quite late, about 1/4 throttle. Stock is about 1/8 throttle: drag racers like it to start sooner, so they solder the hole shut and redrill about 25% smaller. This removes some of the "throttle bog" you get when snapping the throttle at low speeds. BUT: you'll need DYNA coils to keep the plugs clean on the street if you do this mod.   

[05c50]

Thankyou very much for your post HondaMan. I've been working on a 77 550f for about 6 months and could never get it to run just right. The PO had tried for about a year before me. He had cleaned the carbs.(they were spotless),replaced jets,needles,seals and gaskets.After many adjustments(smaller jets,dropped needles,set idle mixture,sync carbs)the bike was rideable but still was rough at 1/4 throttle. After seeing your post about the bleed holes I thought I would take another look(10th time). Although the bleed holes were open and clean,it gave me an idea to check the the emulsifier tubes. The needles would slide loosely through the tubes,but were tight through an extra set of tubes that I had laying around. When I looked into the tube with a magnifyig glass I could see that the tube had corroded away and no longer fit the way it should. I replaced the tubes and now the bike runs like it should.It may even be a little lean now,but I can deal with that. Thanks again for the inspiration look a little further.    Paul

[Loudpipe]

Sorry, I still don't have a Clymer, and it's better to hear from people who've done it anyway...

How much is involved in removing/cleaning/reinstalling the carbs off a '78 750F? One of mine is leaking from somewhere, and they've all been sitting for a few years. I have a fair amount of mechanical experience on cars, but never did have to rebuild a carb (until now). I have a basic understanding of how they work, but I do mean basic.  Is it necessary to buy new parts just to clean them (ie. are all the parts reusable)? About how long would you say it takes? Any special tools needed?

Is there any chance they would be cleaned out and possibly stop leaking by using a can of Seafoam?  I'm not certain exactly where it's leaking from, but the gas will run down the far right (#4?) carb and drip in the crevass right below it on the engine.

TIA.

[ktp1598]

I read over the Clymer and it's not much help 

[750goes]

Removal is easy
Putting them back on  - PITA
Cleaning is easy
Putting them back on  - PITA
Reinstalling is easy
Putting them back on  - PITA
Leaking should be easy to track down - make every thing dry first - NOT with a heat gun..just to be safe...
Turn on the fuel tp and watch where it comes from..
New parts - more than likely are NOT NECESSARY unless you break something on dismanting or reassembly
Most parts are reusable - don't break them taking them apart..

How long does it take - thats your call - but start early and plan to finish late if this is your first time - but get all tools and a work area clean and ready to go - no disruptions apart from toilet breaks are permitted - definitely no alcohol permitted until carbs are remounted on the bike - then you have earned several beers or other forms of enjoyment.

Seafoam ?? don't know - never used it - read up the FAQ section...sounds like nectar of the gods to some members..

good luck

[Loudpipe]

What makes putting them back on such a pain?

Are there any places near the top of the carb that it could possibly leak from? All I can tell is that is runs down the length of the thing and drips off the bottom, so obviously it's coming out near the top or on top of it somewhere.

[750goes]

If the rubber boots are hard because of age- they are not very pliable, and when trying to put them back on they sometimes are difficult to line up ... there are many many topics covering this subject within the forum  - have a search

to find out where it is leaking - if the fuel is coming from the TOP of the carbs - or somewhere thereabouts, then take the tank off and check your fuel lines for splits and leaks, could be a possibility or a leaky petcock valve or connection between the carbs..

 

[flatblack]

Echoing a couple of points from above...

1. You can reuse the various metal parts. Unless you want to work with your carbs often, however, I would suggest getting new float bowl gaskets (o-rings) and installing them during reassembly. If you completely tear down the carb rack, use new o-rings on the fuel transfer tubes that interconnect the carbs (if present) or new hoses and clamps (for the same purpose). These rubber parts suffer the most from aging.

2. Getting all of this off the engine and onto the bench isn't all that hard. The difficulty comes in reassembling things and getting the stiff rubber hoses to fully seat against the carbs, front and rear. Softening the aged rubber with a treatment/preservative product is a good idea -- never use a heat gun for this purpose.

3. Tracking that leak might be a pain. If it's coming from the "top" of the carbs, it's probably either the hose from the tank or one of the interconnect lines. If it's internal, it's probably a stuck float valve, bad bowl gasket or a combination.

4. When reassembling, a bench synch is good idea (adjust the rack's linkages so that the slides rise and fall together). Then, follow the Clymer book on how to adjust the choke and throttle linkages. Lastly, synch the carbs with the engine running.

5. You can try to use a carb cleaning product with them on the bike. Seafoam, Yamaha Carb Cleaner and other products do work in many circumstances. Follow the product's instructions and recommendations. Be patient.

Bottom line: If the bike/carbs have been sitting as you describe, you need to pull them and clean them out. The bike probably will never run right until you do.

HTH...

fb

[dusterdude]

seafoam is a damn good cleaner,wont do squat for leaks.

[Loudpipe]

My thought was that if it was a stuck needle or float or something causing it to leak, it could possibly clean it out and cause it to not be stuck and stop overflowing. However, I could be off base here as I know little about the inner workings of carburetors.

As far as the leak goes, it's not the petcock. the leak is only one 1 carb, and it's on the far right side of the engine, when my petcock is on the left.

Do the carbs actually bolt to the engine, or are they connected via a plyable rubber hose which stretches over some sort of large opening? Do they hard mount somewhere to the bike?

[cmorgan47]

there's no bolt, just the hose clamps around the intake manifold.  once you loosen those--and take all the airbox crap off the back--you _should_ be able to _slide_ them off.  this sliding action may involve a rubber mallet.

it could be a stuck float needle, or rotten orings around the float set.  if i were you, i'd bite the bullet and buy the rebuild kits.  1 per carb, typically about $20 each.  they come with all the gaskets, orings, jets and needles to rebuild it properly.

that and get either a can of "carb dip" to soak the bodies in, or the yamaha stuff you boil....never used the yamaha stuff, but i will be soon on "honda III's" nasty carbs.  carb dip worked fine on "honda II" though.

[Loudpipe]

Holy God! I just called a local shop that works on old bikes to see how much they would charge to rebuild the carbs if I brought them the parts they needed to do it, and they quoted me $400-450.  I think I'll learn to rebuild them myself. That's just rediculous.

At this point, I'm thinking that it's leaking from the fuel transfer tubes.  Turns out that 3 of the carbs are leaking fuel, it's just that the one on the right leaks much worse than the others.  Carbs probably still need to be rebuilt though.

Who sells the most complete carb rebuild kit, or the best quality one?  Do these kits come with instructions on how to clean and rebuild them, or is there some sort of manual I can buy that would do a step by step rebuild?