24-01-16, 12:45 PM
It may be that one of the rubber diaphragms is being / has been pinched upon previous reassembly. Look for any signs of creasing or indentation and make sure the little o-ring is present and in place. Unfortunately as soon as you reassemble the carb tops, it's out of sight, so you can't see if it's in the correct position or becoming twisted as you screw the carb top screws down.
Sometimes they can be straightened out, but if they're old or gone a bit brittle then replacement is the best solution.
Hmm... Wemoto are charging £44 for each single diaphragm:
http://www.wemoto.com/bikes/yamaha/fzs_6...diaphragm/
Another possibility (which I experienced on my 350LC) is that the carb diaphragm has been put in the wrong way, and by that I mean which way the lower part is facing. It may need to be turned around 180 degrees. On the LC it was the carb body itself but different carb design, same principle.
No idea how mechanically minded or patient you are, so you may wish to just get a second set of carbs off ebay, flush them out and try them instead. Indeed, it may well prove a cheaper solution....
Sometimes they can be straightened out, but if they're old or gone a bit brittle then replacement is the best solution.
Hmm... Wemoto are charging £44 for each single diaphragm:
http://www.wemoto.com/bikes/yamaha/fzs_6...diaphragm/
Another possibility (which I experienced on my 350LC) is that the carb diaphragm has been put in the wrong way, and by that I mean which way the lower part is facing. It may need to be turned around 180 degrees. On the LC it was the carb body itself but different carb design, same principle.
No idea how mechanically minded or patient you are, so you may wish to just get a second set of carbs off ebay, flush them out and try them instead. Indeed, it may well prove a cheaper solution....