Please HELP: 83 XS650 when full choked left cylinder runs when off choke both run after warming

[dlum515]

I have an 83 650 and I'm running into a confusing problem. Carbs have been cleaned, new diaphragms, new spark plugs, tuned the carbs to idle properly but having a weird thing when cold starting with choke.
When choked the left cylinder fires and runs but the right doesn't fire till the choke comes off.
So when starting I choke, let the engine warm a little on choke then take it off and the right will fire up. After a little more warming the engine purrs at 1200 rpm and I don't have any issues when riding.
Does anyone have any ideas why the right won't fire with the choke on or can you advise on troubleshooting it?

 

[ckahleer]

Assuming right is too rich, while choke is on and running on only the left cylinder, start turning the mixture screw in on the right carburetor. See if there is a spot it will start firing.
If no go, swap the left and right carburetor enrichers.

 

[jpdevol]

I have an 83 650 and I'm running into a confusing problem. Carbs have been cleaned, new diaphragms, new spark plugs, tuned the carbs to idle properly but having a weird thing when cold starting with choke.
When choked the left cylinder fires and runs but the right doesn't fire till the choke comes off.
So when starting I choke, let the engine warm a little on choke then take it off and the right will fire up. After a little more warming the engine purrs at 1200 rpm and I don't have any issues when riding.
Does anyone have any ideas why the right won't fire with the choke on or can you advise on troubleshooting it?

There are a few things that would cause the right choke to not work.
First would be a plugged passage that extends from the choke tube down through the float bowl, if blocked the open choke will flow no fuel. Spray through the entire circuit to make sure it'

s clear.

Likewise, if the bowl gasket doesn't have an opening for that passage, same result. Sometimes the gaskets aren't punched correctly.

 

[jpdevol]

The next possible issue is the arm that is attached to the choke rod may have slipped to the point it is no longer pulling the plunger on the right carb. It has a set screw that binds it to the rod. Part #50 in diagram

 

[dlum515]

Thank you, I'm starting to think it's the idle circuit that is the issue when choked. I'm gonna pull the carbs off in the next couple weeks and do a more thorough cleaning.

 

[dlum515]

It's been a while but I finally resolved the issue. I thoroughly cleaned the carburetors with an ultrasonic cleaner and re-assembled and the issue didn't go away. In the process though I discovered the problem. The carb boot for the right cylinder with the choke problem wasn't sealing properly. The threaded bolt hole had stripped and wasn't allowing enough torque to seal the gasket. So I had an air leak at the right carb boot. I used a helicoil thread repair insert and bolted everything back up and the choke problem was resolved.