KZ400 Timing(?) Question

So I've been running my 11th Hour Industries 2-1 intake with a VM32 carb for a couple of years now. Bike runs nearly perfect, except for one very weird thing...

My left plug is reading lean while my right plug is reading rich. The 2-1 is straight, not the 90 degree bend... so I can't imagine why the fuel would be flowing to one cylinder more than the other.

Timing?
Compression?

I've checked both and don't recall seeing any notable issues. Last compression test showed 120 or 130+ on both cylinders.

a compression test won't usually show if one cylinder has valve clearances out of spec. It could be that one valve is not sealing all the way when on the highway at full speed, but it will seal after it cools down, or riding slowly.