Those are GREAT units!!!! I have one like it only smaller......way smaller but I can still so a jug in it.
I've tryed about everything you can think of in mine but so far I like a product called AWESOME from the Dollar store about the best. Tryed Dawn, Dawn and Tide which wasn't to bad. Simple Green wasn't bad either, Purple Power but was running temp way to hot and turned carbes black/dark grey.
I use the AWESOME at about 100 deegrees and get VERY good results. Carbs/parts come out nice and shinney.
I was wondering what temp your using the Pinesol at to get your results? That piston looks new!!!! Did you you Pine or Lemon scent?? LOL