Introduction: How to Clean a Motorbike Carburettor Using an Ultrasonic Cleaner

We all know the old saying that a grain of sand in a carburettor can stop the most powerful of motorbike engines. And it’s true. In the World of carburettors, cleanliness is king. And if you've grazed a knuckle or two removing the carb from your bike, you might as well give it your best shot at cleaning by using an ultrasonic cleaner.


Ultrasonic Carburettor Cleaning fluid supplied by Best Ultrasonic Cleaners (UK website)

Step 1: Carburettor Cleaning With an Ultrasonic Cleaner

Having owned motorcycles on and off for more years than I like to admit and having rebuilt a few engines, from old BSA Bantam (D2), Norton Commando 750 (fastback) and a Ducati (250 Desmo), back in the day I would soak the carburettor in a bucket of degreasing solution for an hour or two, then rinse with water and blow it off with an air gun. Simple, but not really very efficient.Technology has advanced over the last few decades and when it comes to cleaning a carburettor and related components, the accepted best practice these days is to use an Ultrasonic Cleaner.

Without getting too bogged down in the technical detail, an Ultrasonic Cleaner has a component called a transducer that generates sound waves, that in turn produce microscopic bubbles that very effectively dislodge dirt, grime and petrol residue from the intricate parts of a carburettor that would otherwise be almost impossible to get to.

Step 2: Buying Your Ultrasonic Cleaner

I have a mantra about the selection process. Obviously the price is a main consideration, but above that - SIZE MATTERS. I can't say that enough, so I will repeat - SIZE MATTERS!!!

It's no use buying a small machine to save some money if your carb won't fit in the tank.Try and get this right first time. And the best way is (if you can) to actually measure the overall dimensions of your carburettor. This isn't always possible if the bank of carbs are still fastened to the bike and it can still end up being a "guesstimate". Also, you will be removing some of the parts such as float bowls, slides etc and this will reduce the overall required tank size. I think that if you can afford it, get something a bit bigger than you estimate. If you try to cram a small tank full of parts, the cleaning will not be as efficient as putting them into a larger tank. As the saying goes, "what will hold more will hold less". You get the idea?

Note: Most ultrasonic cleaners are supplied with a wire basket. This is going to be smaller than the actual tank size and it is the basket dimensions that matter. If you take into consideration that a steel basket in the machine, it can reduce the workable size by up to 8mm all round. Click here for a chart that shows basket / tank sizes.

Step 3: Using the Ultrasonic Cleaner

Using an Ultrasonic Cleaner requires no special knowledge or skill. All that is needed is water and some carburettor cleaning fluid to put into the tank. The unit is then plugged into a domestic power socket and the built-in heater raises the temperature of the water & cleaning solution mixture to around 60 degrees centigrade. Place your carb in the tank and turn on the ultrasonics. Normally around 15 - 20 minutes is a sufficient cleaning time. Remove the carburettor, rinse and leave to dry. Not only will the carb be deep cleaned internally, but the alloy casting will look bright and clean. The more parts you can remove, the better the cleaning will be.

If you want to look at different models of Ultrasonic Cleaner, click here.

if you want to ask a question, click here.

Step 4: Thanks To....

Many thanks to my mate Steve Bostock (shown in the above photo) who's carbs are shown being cleaned in the post. :-)

And a little plug for my small one-man business,, who supply the machines.

Step 5: More Examples From a Honda CB350/4

Another customer send "before and after" photos of a set of carburettors off a Honda CB350/4 motorcycle after using an ultrasonic cleaner.