1981 Yamaha XS400 left cylinder not firing

Jeremy

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Hello I have a 1981 Yamaha xs400 that I bought for 50 dollars and rebuilt. The latest problem is left cylinder does not fire. What I've done so far is switch the spark plugs, and ignition coils that didn't change anything. Then I did a compression test they were both around 150 psi. Finally I sprayed starter fluid into the intake of the cylinder that wasn't working and that seems to bring life to it, which makes me think it a problem with the carb but I can't see any problem with it. The jets are brand new and definitely not clogged. I thought the starter fluid would help me rule out a timing issue
 
IMG_20220318_144159.jpg
IMG_20220318_144159.jpg
 
Really inspect the pilot jet, and the idle jet screw. When I rebuilt my carbs, I was fighting a lack of idle jet adjustment and I finally solved it by reaming all of those passages *that I could reach) with a single strand of copper wire. The pilot jet was really clogged and removing the idle jet screw and reaming that out is what really go it working for me.
 
Thanks that about lines up with what I did. I ended up going a couple sizes bigger on the pilot jet, and that seemed to have fixed it
 
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