Will carbs run lean or rich if choke plunger is not sealing?

[XS650D]

Also if the seal under the choke body is leaking would that cause a lean or rich problem.
I am trying to diagnose a carb problem on my left side that I have been unable to solve in 5 years
of playing with it. I have to have the fuel or air screw out min 3 full turns just to get it to run somewhat
correctly. If I hold the throttle at say 3000 rpm when the bike is good and hot the carb will fart bad!
I believe its a lean condition. I dont have points (Pamco digital ignition) new reg and rec ect.
Pipes are new and sealing well on all connection points. I've had the carbs of so many times
ive lost count, floats good, needle rings new, tried flipping bowls, no change.Its either something internal
that I cant see. As per 5-Twins the 76/77 model year carbs are not compatable with any other year.
Cannot find another left hand carb body on line for those years. I think that the 76 year may not work either
as it was not on a rack pivot but not positive. Not sure if theres a probe small enough to run thry the air screw opening but with a magnifying glass and a light see no internal damage. What usually happens on those 2 years on the carb if the screws are turned in to tight? I have what I think is the original air /fuel screws and they look slightly bent on the tip but no material missing. Thx for any advise. The bike rides and handles so nice now its a shame I cant get it to run rite !

 

[robinc]

Also if the seal under the choke body is leaking would that cause a lean or rich problem.

If a choke body gasket is leaking you'll probably be able to hear a "chirping noise" at idle if you listen closely.

Could also be a leaking throttle shaft seal. Will "chirp" as well. If you haven't replaced them.

Use a length of aquarium hose as a "stethoscope" and you might well find where it is leaking. Works extremely well.

Tip from Mailman.

 

[XS650D]

Thx,did already change the throttle seals on the shaft, balanced carbs with flow meter.
No chirping at all just popping noise when engine hot and hold at 2500 to 3 grand on left side only.
I have swapped everything that can be swapped and no change .Havent looked at choke yet so
thats next but I have my doubts if that could cause a lean condition,dont smell or see any fuel on that carb.
will squirt some WD 40 or starter fluid around that choke before pulling apart.

 

[5twins]

I think a leaky choke plunger would cause a rich condition. Maybe your mix screws aren't the right ones? This is what they should look like, with a small knurled head .....

The earlier '70-'75 screws look like they might fit but are tapered differently so would meter differently .....

 

[XS650D]

k Thx will check

 

[TwoManyXS1Bs]

The choke plunger seals 3 channels.
- The bottom rubber tip seals the fuel from the float bowl.
- The plunger body seals (on its sides) the air inlet from the bottom (atmospheric) side of the diaphragm chamber.
- The plunger body also seals (on its sides) the resultant air/fuel mix from the first 2 channels that goes into the carb throat (choke discharge port).

So, the answer is: Yes, the carb can run rich or lean if the choke plunger isn't sealing correctly...

 

[XS650D]

Wow! Perfect info. Thx TWOMANY. That may just be my issue all along.
Regards
warren