Cleaning Carbs, especially small ones

[Ross365]

I’ve cleaned up a number of carbs, usually doing the best I can with my ultrasonic bath. The problem with this is that carbs tend to have small internal galleries and I’m not sure how well the ultrasonic waves get down there; I suspect not well. Some of the galleries utilise welch plugs (core plugs) https://en.wikipedia.org/wiki/Core_plug to seal dead ends in the castings. In the past, people would remove these for cleaning, but replacements for these can be very hard to obtain now.

Other than just simply immersing the carb in the cleaning solution, and putting it in the cleaner for 5 or 10 minutes, does anyone have any clever means of improving on this?

 

[Morrisman]

I've heard of putting hot water/cleaning fluid in the ultrasound, to give a bit better efficiency.
Plus, I'd imagine the whole carb vibrates a little too, not just the fluid.

 

[Ross365]

So, you're saying fill the whole bath with cleaning fluid solution and sit the carb in a basket, as opposed to placing the carb in a plastic container which is suspended in plain water? Yes, I see the logic there, the only downside is you'll be using ten times the quantity of the cleaning additive, but better to do that and have it work, than skimp and fail.

 

[tom2207]

dive gear I do in vinegar and water in the ut bath ,, glasses I do in a cap of cleaning fluid and a fair slosh of meths and topped up with hot water ,,, seems to work well . but I have a bath with a heater in it so I turn it on to heat and it comes up to sort of 80 degrees c ...i use the same fluid for a week or so then just throw it out and start again ,,, if im in a rush I boil the kettle and make a new batch of fluid in the bath and off it goes again ,, the heat definitely makes a big difference though.

 

[colnerov]

Hi, In the past, before the ultrasonic bath, I've had good results with thinners because it removes the varnish you get left behind from petrol better.

Colin

 

[Ross365]

In the days when my job needed very clean stainless pipe fittings, we reckoned that Decon 90 was the best ultrasonic cleaning additive on the market, but it is too caustic to use on a carb. I'm presently using a cleaner made by Allendale, specific for carbs. Agreed, increasing temp is good provided there is no chemical attack on materials (which I have seen on some electronic gear).

As per post #5, the issue of what is the "muck" that you're dealing with comes up. Petrol residues are organic and so thinners should be good ( but don't overlook the health and safety issues of using thinner in an ultrasonic bath). But solid particles (perhaps rust) seem to get in to carbs, so vinegar, or better still maybe citric acid, may be useful.

I am old enough to remember when everyone used Freon (now banned) in their baths. Not only was it a good solvent, but it was also very dense and the ultrasonic waves loved that!

Another trick I've been playing is making use of my vacuum oven. I put the container with the cleaner and the carb in there, and pump it down to vacuum; if there are any air pockets trapped in the carb, the air gets pulled out and and you see bubbles appear as the vacuum come on. Then let down to atmospheric and transfer to the cleaner.

 

[winchman]

I use a degreaser called Elbow grease its £1.
Latest carb I used washing up liquid and it worked fine as I had run out

 

[Migmac]

When I’m doing chainsaw carbs. I use carb cleaner and squirt it down every hole until I see it coming out somewhere. Then a quick dip in petrol to wash of the carb spray, same for lawn mower carbs.

 

[8ob]

I use a large glass jar filled with brake cleaner, I submerse the carbs in that and put the lid on. Normally leave them a few days , then attack with an air line before putting them in the ultrasonic tank, I only use the ultrasonic for the final clean.

Bob

 

[Agroshield]

...the issue of what is the "muck" that you're dealing with comes up...

Maybe you need a multi-step approach with different sauce each time: a detergent first to remove any grease, then a solvent to remove residue, then something to remove corrosion followed by a final deionised rinse.

 

[Pete.]

For petrol varnish deposits try immersing it in toluene if you can get some and if you are happy to use it. Make sure there are no plastic parts in the carb and keep ventilated.

 

[MCKDAVID]

I use a large glass jar filled with brake cleaner, I submerse the carbs in that and put the lid on. Normally leave them a few days , then attack with an air line before putting them in the ultrasonic tank, I only use the ultrasonic for the final clean.

Bob

Same, more or less, don't always have the time to store for a few days unfortunately, generally start with a good clean of the outside, in brake clean with a bowl an brush, then a good spray down before the strip down, cleaning every thing first before it goes in the tank. Definitely helps keeping the fluid cleaner so it lasts longer. One or two passes through the ultrasonic, depending on general condition, and how badly it was running... Sometimes, will revert to sticking in the jar with brake cleaner, if it idles badly, usually the small passages on the idle circuit are still clogged.

@Ross365 interested in your comments on vacuum oven? Could you share some details on how you get on... Always interested in easier ways of getting them cleaned.

 

[Morrisman]

So, you're saying fill the whole bath with cleaning fluid solution and sit the carb in a basket, as opposed to placing the carb in a plastic container which is suspended in plain water? Yes, I see the logic there, the only downside is you'll be using ten times the quantity of the cleaning additive, but better to do that and have it work, than skimp and fail.

Depends on the size of the bath, and the quantity of carbs you do. My friend has a bike garage and clogged carbs is becoming more and more of a thing nowadays. Guys park their bike up over the winter and wonder why it runs like a bag of spanners four months later. He has a bath that will take a bank of four carbs, and it's running several hours every day.

 

[zzr1200]

I tend to use washing up liquid and water, set the ultra sound cleaner at maxium temp and the longest time, depending how blocked/dirty the carb is, I'll put it in twice then blow out with compressed air.

My 338 top handle chainsaw took 3 goes to clean the carb. I purchased the saw new, but left fuel in it for years had to place fuel lines, fuel filter and a carb kit.

 

[HydrocarbonPrimate]

Apparently in aviation they use or used to use, MEK, Methy Ethyl Ketone for removing varnish deposits, I purchased some from a popular auction site, but its very bad for your liver, i think it can be absorbed through skin so gloves and masks etc, i've used it to soak carbs in sealed container then cleaned out with brake cleaner, the carbs I had wernt particularly full of deposits so hard to tell how effective it was.

 

[MCKDAVID]

I tend to use washing up liquid and water, set the ultra sound cleaner at maxium temp and the longest time, depending how blocked/dirty the carb is, I'll put it in twice then blow out with compressed air.

My 338 top handle chainsaw took 3 goes to clean the carb. I purchased the saw new, but left fuel in it for years had to place fuel lines, fuel filter and a carb kit.

Aye fuel is junk now, not ideal but I tell customers to empty the tank, and start and run dry, or fuel stabiliser in the tank, but just don't leave it with normal fuel or 2 stroke mix ( which is worse). Daft really, as it keeps me busy doing overhaul and re starts, but the modern ethanol based is just junk, even after a couple of months...

 

[zzr1200]

Aye fuel is junk now, not ideal but I tell customers to empty the tank, and start and run dry, or fuel stabiliser in the tank, but just don't leave it with normal fuel or 2 stroke mix ( which is worse). Daft really, as it keeps me busy doing overhaul and re starts, but the modern ethanol based is just junk, even after a couple of months...

Aspen 2 and 4 is the answer, expensive but worth it in the long run...I've not had any problems since I started using it in my chainsaws or lawn mover...

 

[Morrisman]

Aye fuel is junk now, not ideal but I tell customers to empty the tank, and start and run dry, or fuel stabiliser in the tank, but just don't leave it with normal fuel or 2 stroke mix ( which is worse). Daft really, as it keeps me busy doing overhaul and re starts, but the modern ethanol based is just junk, even after a couple of months...

When I lived in the far east I used to go offshore for six weeks at a time, so the carbs had to come off the hot rod and the bike, be drained, compressed air, then a bunch of WD40 sent in.

I learned that the hard way, when 6 weeks at 35c every day effectively stove enamelled the carp fuel residue into every tiny orifice. I thought about fuel stabiliser but nobody I knew there rated it much.

 

[zzr1200]

Very Nice....

 

[mangocrazy]

With bike carbs I'd say the trick is to dismantle the carbs as far as you can into their component parts prior to ultrasonic cleaning them. This includes emulsion tubes, in fact anything that can be removed from the carb body, take it off. Then put all the small pieces into a muslin or nylon bag with a drawstring so they can't escape and put that in the cleaner with the carb body. With the Mikuni carbs on my LC it's also recommended to remove the brass balls on the side of the carb facing the airbox and clean the crud out from behind there. Tap the hole with a suitable size metric tap and plug with a grub screw. I was horrified at the amount of crud that appeared when my LC carbs were dismantled during its dyno session.