mixture screw question

[Jimbo W]

If a mix screw o ring was bad would this result in a lean or a rich condition?
Still trying to get my '80 G running well on left cyl. Wet fouling of plug not solved after 3rd time of carbs off.
Float height @ 27mm, float valve appears to be working (shuts off fuel if floats moved manually), jets all original, squeaky clean in there, diaphram good, airbox original. Was running fine until I started fiddling.
Bit of smoke from left cyl when throttle is blipped so wondering if excess fuel has washed the bore. Compression test needed I think. Possibly should replace float valve o ring? Been squirting a bit of carb cleaner around so rubber could have been affected?
Another question: is the butterfly shaped bracket between the carbs needed? It helps to omit it while the carbs are going on & off regularly!
Many thanks, great forum.

 

[5twins]

I think a bad mix screw o-ring would result in a lean condition. I think it could allow extra air to be sucked down in around the screw from the top. Yes, check the float needle seat o-ring. It's somewhat common for them to go bad.

You say the floats are properly set @ 27mm, but do you have brass or plastic floats? 27mm is correct for the brass floats but if someone replaced them with plastic ones, the setting is different (22mm).

 

[Jimbo W]

Yep, I thought lean so prob not the issue. It looked ok. Both at 3 turns out. Will try turning left one in a tad before carbs come off again.
Got brass floats, not leaking. Swapped pilot jets left to right in case I'd hogged the bad side out when cleaning but no change. Blew cleaner through air jet so should be ok. Butterflys both almost closed with no throttle.
Don't think it can be ignition - swapped plug leads/plugs over but problem stayed on left. Battery is fully charged.
Appreciate your reply.

 

[xjwmx]

If you're worried about air getting past the o-ring put some blue tack in the tunnel to plug it and see what happens. You can use the extra to clean ear wax out of your earbuds.