Yamaha 90 AET black rubber plug

[villeva1]

Hello.

I did clean my 1987 YAMAHA 90 AET carbs today ans noticed that one of two injectors per carb was plugged with black rubber plug.

I removed those plugs and i noticed that the injector is size 60. Is that injector for idle running or what? And why it is plugged? My engine runs invidle very good.

[99yam40]

put them back in or replace with new ones
they are there to force all of the fuel to come through the main jets for metering.
If they are not in place then there will be fuel from both pilot and main jets during higher RPM causing a rich condition

If you look closely there is a passage between the two above the rubber plug

By the way they are not injectors