Gift horse - part 4

Another problem that became apparent right away was the condition of the engine internals, as you will see in the next horrifying photo: this poor bike had been left to rot out in the open, and, in addition to old fuel, water also obviously got in, causing damage to the carburetters and, downstream, to the heads and cylinders. Beyond? who knows!

Above: a peek inside the right-hand cylinder head reveals a serious situation, and as (bad) luck would have it, the valve remained open this whole time. The prognosis for the rest of the engine internals is looking bleak at best.

This motorcycle is equipped with the so called "flat-top" Bing carburetters, a short-lived variant that I understand was in use only a couple of years. Our right-hand one was severely clogged with the same sediment or limescale you can see above, which had stratified in the float bowl. Once that was cleaned, it revealed that the float bowl itself was punctured, so needed to be replaced anyway! The jets assembly was completely seized and required a drill to remove it, destroying it in the process, and allow us to clean the rest of the fuel passages.

If this is what the float bowl looks like, I dread to think about what happened further down the line.

Above: with hole, below: no hole.

Some other parts after cleaning, fine to reuse:

The butterfly valve and actuating mechanism was removed to clean its housing and also replace the o-ring. This requires grinding down the two screws, which then obviously have to be replaced:

New jets, needles, gaskets and diaphragms were procured, and thus was the right-hand carburetter reassembled, ready for use again: