You answered your own question. Also, you may have an overfilled oil situation. Store your bike on a wheel chock that will keep it straight upright then you shouldn't have that oil pooling problem into the left cylinder.
I had the same problem. The Service Bulletin solved the noise. Call you dealer and ask the service dept. to look up.
BMW R18
PUMA - Service Bulletin
S1 13 07 21
Loud / Noisy Fuel Pump
Reply
Since it is an exposed system BMW recommends to clean it thoroughly and re lube the splines with TS-60 spline lube. A small stiff brush like an acid brush works well.
https://www.shopbmwmotorcycle.com/products/ts-moly-spline-lube-2-oz
There are probably many less expensive alternative gear...
I sold my Indian and bought the BMW R18 FE and never looked back. It handles like a BMW. It is much more agile in the twisties and weighs approx 70 lbs. less. Low speed "parking lot" manuevers are about the same, but you get used to it.
The Bell Bullitt is an excellent helmet with a giant eye cut out. Not the quietest helmet, but I always wear earplugs anyway. They do run small so order up one size.