Pretty cool. Nice job.
Everbody should have one - not just for your bike either!
Excuse me sir, I'm supposed to put this stopper where???!!!!
Here's a suggestion for a V2.0 for your prime & burb tools:
Combine them. Use some clear flexible tubing off the funnel. Add rubber stopper to end. TA-da! Fill up to prime. Pour in balance. Start bike & wait for back flow. Could get even fancier by adding a shut off valve just behind the rubber stopper.
I guess I'm just old tech. I made a squeeze bottle that I can actually squeeze the oil out of. No burp tool for me. Never had that much of a mess. Just lucky I guess.