Carburettor Cleaning

Ultrasonics for carburettor cleaning is achieved in my industrial ultrasonic 80 litre tank with a power density of 20 watts per litre (much greater than bench-top units) at 40kHz frequency.  The cleaning solution is water with a detergent specially formulated for the non-etch cleaning of aluminium alloys.  This is heated to 55 deg C, the ultrasonic energy making the solution cavitate (the constant formation and collapse of airless bubbles) causing adhering contamination to loosen and fall away.  As a result ultrasonics does a good job of loosening gum, fine dust, silt etc.

My 3-stage process will loosen gum and crud, but it can’t be flushed-out if jets and other parts are in place.  So carbs need to be sent fully stripped of all components (with the exception of any butterfly valves if these are difficult to remove).  Be sure you hook-out any tiny O rings, washers or light press-fit parts otherwise they’ll almost certainly be vibrated loose and may be lost (snug press-fitted parts are ok).  If you want the components cleaned too, put all the relevant bits in separate marked poly bags and each lot will be kept separate.  Pack and pad well in a sound carton!  The same packaging will be used to return your carbs.

It is recommended that you do not undertake dismantling and reassembly unless you are experienced and have the relevant drawings to ensure correctness and completeness.  Dismantling/rebuild service available if required, but not flow testing.  Final set-up and tuning will always be required after return.

I cannot guarantee that all passages will be cleared as a fine passage filled with hard gum is possibly insoluble, and it’s impossible to check.  That would be very unusual as gum forms in the bowl and lower main nozzle area rather than the carb body passages. 

I have had only one case so far where a customer has said that a running problem had remained, but they couldn’t state the cause, and may not have been due to an internal blockage.  However ultrasonics cannot guarantee to clear everything.  A broken sewing needle in one jet required a different approach!  Internal corrosion could be a problem with ancient or abused carbs. 

Pre-war pot-metal carbs (a cheap alloy with high zinc content, also known as Mazac or Zamac) are particularly prone to instability known as ‘zinc pest’.  It has a tendency to spontaneously distort, crack, pit and even shatter with age.  This is usually self-evident and you would be able to see that there’s no point in having cleaning undertaken.  With higher purity metals available after the war this ceased to be a problem and is unlikely on anything post 1950.

However there’s nothing better than professional ultrasonic carburettor cleaning for removing internal and external contamination. 

Ultrasonics won’t greatly improve oxidation of the outside of carbs (this is a chemical conversion of the metal itself causing etching, even pitting) and if wanted can usually be improved cosmetically using other techniques.  However, they have to be inspected first.  It may not be possible to replicate the manufacturer’s original finish but can usually be made very acceptable.  Some zinc alloy carbs can be left clean but very dull by ultrasonic cleaning but again can usually be brightened.

Cleaning price guides (subject to confirmation) – post / courier / insurance charged extra at cost + £5.

Simple carbs CASTINGS ONLY:

1 carb £20, 2-£35, 3-£50, 4-£65.  Cosmetic cleaning if required £10 per carb.

Complex carbs CASTINGS ONLY (eg Webers):

1 carb £25, 2-£45, 3-£65, 4-£85.  Cosmetic cleaning if required £12.50 per carb.

Simple carbs and accompanying internal parts:

1 carb £25, 2-£45, 3-£65, 4-£85  Cosmetic cleaning if required £10 per carb.

Complex carbs and accompanying internal parts (eg Webers):

1 carb £30, 2-£55, 3-£80, 4-£105.  Cosmetic cleaning if required £12.50 per carb.

Turnaround is usually about a week. 

Please contact me to discuss your particular carbs.

Fuel and additive gum, almost insoluble - can be done

Yamaha Mikunis.........restored, incuding re-plating of steel parts

Land Rover Solex (plus Mikuni). SU Carbs - owner reported much improved running too

Carbs come in all condition. Full works on Bings - ultrasonic, cosmetic clean, polish tops, replate steel pieces

As received, stripped but on rail. Ultrasonic clean only

Mucky Twin-Choke Dellortos. After ultrasonic washing only

Ultrasonically cleaned but needs improving. Nothing can replace erroded alloy

Ducati Dellortos and close-ups

Close-up and one finished, the other part finished

Early Zenith........again functioning

Weber needing improvement...................not perfect, but good

Barn carbs and inside view

Cleaned................cosmetic appearance can be enhanced

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