As I’ve mentioned before on this site, getting older carbs to work well and effectively can be an uphill battle. Keyster carb kits, or a complete new VM34 Mikuni from Allens Performance can be pricey but do save a lot of buggering around and you can cut out a lot of hassle.
With both Husky WR250 and TT500 projects underway I took the advantage of working in the office with Roger to have a go with his Ultrasonic cleaner. It’s a model from Maplins, the Professional Ultrasonic Cleaner 8050-H and has a 2.5l capacity. This is slightly too small to completely submerge a decent sized motocross carb (like a VM34), but it does have a heater and programmable settings.
Not having any specific agent to put in it, we went initially for a coffee brew (a Nespresso Roma to be precise) and then for various combinations of Irn-Bru and ginger beer. The latter fizzy drinks, and I think full fat Coke would be good for this also, provoked a lot of activity in the bath.
After cleaning both carbs, some of the larger muck on the outside of the carbs was still stuck there and having a handy toothbrush along would be good. However, the slides come up really well and a regular clean will prevent throttle sticking for sure.
I’ve not tried the TT500 carb, but the VM34 on the Husky seemed improved during the brief garage-based testing. Time will tell, but a worthwhile exercise.