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Hi all.
Any advice on cleaning the carbs with an ultrasonic cleaner?Can I lob the lot in or should I remove plastic parts and/or jets first?
I’m wondering if the plastic slide and floats could be damaged but of course I’d rather put them in as they need cleaning too.
Any other insights I should be aware of?
Cheers, Mark.

Obvious, but remove any fibre washers. Don't ask me how I know....

Disassemble everything. You’ll get a much better cleaning of the passageways if the jets are removed. Similarly there’s no point in cleaning with the o rings in place as the o rings need a clean surface to seal upon properly.

It also gives you a good opportunity to properly inspect for corrosion or wear on all individual items. Pay particular attention to the emulsion tube and needle.

Personally I don’t put floats or the plastic float bowls (later carbs) in but depending on the cleaning fluid you’re using it probably does no harm to.

Don’t forget to also pick out the o rings and washers that sit beneath the spring on the adjuster screws. Not unheard of for these to be left in as they aren’t always obvious and then on reassembly put in extra ones which doesn’t help at all!

After cleaning make sure all the passageways get blown out with compressed air, or if you don’t have an airline then a spray of carb cleaner.

And of course, rebuild them with all new o rings and gaskets.

I have seen some carbs where the soldered (or whatever) plug for the drillings has come out, which will cause no end of running issues. Not sure what the failure mechanism is- whether corrosion or fuel or vibration or bad luck etc but I imagine it’s probably a low temperature solder or something so if you’re using a heated ultrasonic tank perhaps don’t go too crazy with the temperature. 50 deg or so is probably sufficient for cleaning and safe for the carb (I’m excluding plastics from that statement!)

This post has some pictures and reference to the missing blanking plugs I mentioned:

lemans wrote: ↑25 Apr 2022 18:25




this hole in the rear carburettor wasn't plugged off as should have been.
the front carb had it plugged and according to all manuals, drawings and schematics I believe the hole should be plugged
it also confirms the observation of not being very responsive to the idle-mixture adjusting screw.
put some JB-weld on/in and rebuilt carb

Thanks very much for the concise reply Tom.
I’ll keep a look out for unexpected holes too!

Best to avoid putting fingers into the solution when active and keep the carbs clearly separate or do one at a time to avoid accidental swapping of components.