Left Cylinder Running Cold

[asmcdaneld]

I have a 78 xs400, and I have a problem with the left cylinder. It runs cold. Before I start at it blindly, I am seeking some guidance.

I have just installed a pamco ignition system (http://xs400ignition.com/).
Cleaned carbs and replaced needle and seat. Checking float levels before re-assembly.
New plugs.

* I do not smell fuel.
* The engine runs smoothly, but seem a little under powered.

Should I check coils first, or left carbs?

Scott

P.S. One cylinder running cool would not be timing right?

 

[OleDoc]

See if you have spark.one cylinder running cold means it's not firing

 

[asmcdaneld]

The problem was the petcock diaphragm was stuck. No fuel was flowing in the prime position. I cleaned the petcock, verified diaphragm was not torn, and replaced the o-ring. Once it was re-assembled, switched to prime and chocked, fired immediately.

 

[xschris]

Fuel should only flow without the motor running when set to prime. In the on and reserve position it should only flow with the motor running. This is for the factory vacuum petcock. One side running colder than other side is often an out of sync set of carbs. Use a manometer to set them if you have not done so lately or ever