Leaking carb.

[545863]

I posted a piece recently about my CB100N carb leaking petrol after it was ultrasonically cleaned and rebuilt. The problem was not the float bowl leaking so I assumed it might be a worn float valve seat, (new ones are not available as a separate part). Looking more closely at the seat it looked slightly rough and dull in colour. I cleaned the seat with a tiny amount of grinding paste on a cotton bud held in a cordless drill. I then polished the seat, again with a cotton bud in the drill with a small amount of brass polish. I then sprayed some carb cleaner into the seat. The carb now works perfectly with no leaks. I assume that the ultrasonic cleaning process must have left some form of deposits on the seat causing it to leak?

[Bryanj]

Probablynot, just did a set of 400 carbs ultrasoniced twice and they still smell like an old lawnmover.

Stale petrol varnish is really hard to get rid of only worse thing is stale ethanol

[McCabe-Thiele (Ted)]

On my 400/4 three carb sliders that hold the main jet were seized solid in the Carb body due to standing unused for some 10 years. I tried Diesel,Carb cleaner & a variety of solvents to release them without any success. At that time I did not own an ultrasound cleaning bath.

In the end I soaked them overnight in fresh petrol in a plastic type food container with the sealed clipped lid.
After about 12 hours the petrol turned  brown, I renewed the petrol repeating the process for several days. Two freed off in the first 36-48 hours or so. The last one iirc took 4 days to free off using just hand pressure to push them out, I did not want to risk any damage. I used Carb cleaner & Brasso wadding afterwards to clean/polish the inside of the carb body.