1991 fj1200 smoking after warm up

[Pat Conlon]

^^^ Yes, that's a good tip

After your check on the mechanical linkage, next check for vacuum leaks, both on the intake carb boots and the vacuum line going to the advance module (connected to the port off the #2 intake)
Pull the rubber line off the port, suck on it....you should not be able to draw air thru the line, if you do, you have a vacuum leak. Bad for #2 cylinder. If you do have a leak on this line, it's either a crack in the line itself or a fitting or a ruptured diaphragm in the advance module. The line/fitting is an easy fix, the module not so much. As a.graham points out above, you can cap this vacuum line off with no adverse effects.

Only after these checks, try adjusting (in) your Idle mixture screws

[Bones]

Yep, rule out mechanical first, a hanging idle on a warm bike is a indication of richness.
Try turning your idle mixture screws in 1/4 turn, see if that helps.

Pat, My thoughts are completely opposite to yours. A hanging idle after revving was a sign its lean so you screw the mixture screw out to make it richer, and revs that drop below idle speed after blipping then rise are signs it rich so screw the mixtures in.

Is it possible carbs act differently in the Northern Hemisphere compared to the Southern Hemisphere,  just like how water spins the opposite way down a drain here compared to up there.

[ribbert]

Yep, rule out mechanical first, a hanging idle on a warm bike is a indication of richness.
Try turning your idle mixture screws in 1/4 turn, see if that helps.

Pat, My thoughts are completely opposite to yours. A hanging idle after revving was a sign its lean so you screw the mixture screw out to make it richer, and revs that drop below idle speed after blipping then rise are signs it rich so screw the mixtures in.

Is it possible carbs act differently in the Northern Hemisphere compared to the Southern Hemisphere,  just like how water spins the opposite way down a drain here compared to up there.

I wasn't going to mention it but seeing as how you decided to pick on Pat  , this guys problem is not even a hanging throttle. His problem is the idle speed increases when it gets hot. A hanging throttle is when the revs are slow to return to idle when the throttle is backed off after revving.

Noel

[Pat Conlon]

Yep, rule out mechanical first, a hanging idle on a warm bike is a indication of richness.
Try turning your idle mixture screws in 1/4 turn, see if that helps.

Pat, My thoughts are completely opposite to yours. A hanging idle after revving was a sign its lean so you screw the mixture screw out to make it richer, and revs that drop below idle speed after blipping then rise are signs it rich so screw the mixtures in.

Hey Tony, yes you are correct, a lean problem will hang the idle, but the OP suggests this problem happens after the bike is warm. A lean problem usually gets better as the bike gets warm. A problem with a rich setting on the idle screws, gets worse as the bike gets warm.
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

Thinking about this more, I think Tony (Bones) has better advice.
We know the factory FJ settings on the idle adjustment screws are set lean to begin with...
....so try turning your idle mixture screws *out* in 1/4 turn steps.
Keep notes on your settings, that way you know what to do to go back to your original settings.

[Ndulucky13]

It ended being the "boost" line or diaphragm I plugged that vaccum port on the carbs and all is well now!