Twice in the last 6 months my cylinder 3 valves have burnt up. What can be causing this?

Cylinder 3 piston is the cleanest out of all 4. Picture is after wiping them down.

 

Fuel while also igniter is also a means of "cooling" things down in the upper cylinder head. Wondering if the injector for #3 is pulsing properly and/or atomizing/dispencing the fuel properly....if its squirting the fuel like an old style water pistol, I believe this could be end result.

 

That's what I'm leaning towards. I'll replace them.

 

We see this all the time it's caused by worn out valve guides as they allow the valve to rock and burn. Need to replace the guides and rebuild the head. We can do it if you want to ship the head over.