Right Cylinder Running Richer Than Left


XS650 Member
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Ontario, Canada
Hey guys, new XS650 owner and first time poster.

I'm working on tuning at the moment and I'm having a hard time figuring out why the right cylinder is running richer than the left. This is also my first non dirt bike motorcycle and i'm not super well versed in older bikes.

Some details:

Cam chain & valves adjusted. Boyer Ignition, timing set properly. Hugh's PMA with fully charged battery. VM34s with uni filters. Pandemonium ya mama exhaust. Compression 150psi in both cylinders.

Some things I have tried:

-Checked for vacuum leaks with starter fluid spray
-Swapped plug wires/sides of coil
-does not appear to have exhaust leaks

Today I swapped the carbs from one side to the other. Warmed up the bike, put in fresh plugs and took it for a ride. The end result is pretty much exactly what I have always been seeing. Evidence the right cylinder is running richer than the left when looking at the plugs after as seen in the photo.

The only thing I have not tried is a proper carb sync. Only a bench sync to this point. I have ordered a carb sync tool, and will try that when it arrives.

All this being said, the bike starts easy, idles well, and runs really well out on the road. Great throttle response, pulls hard and no stumbling or popping. I'm just perplexed as to why i'm seeing this difference no matter what.