I used SimpleGreen Automotive cleaner/degreaser. Available at most car-parts stores in 1 gallon containers.
Both Robbie and I were amazed how soaking parts would actually get the gunk off better than most "solvents". Certainly better than using flamable and volatile chemicals. Actually smells much less than traditional SG. Rinsed multiple times after done with regular H2O, then distilled H2O and blew out with compressed air. Was shiny as new after a day of soaking and rinsing. Worked wonders on the cam gears, and all other varnished parts.

Steve
Both Robbie and I were amazed how soaking parts would actually get the gunk off better than most "solvents". Certainly better than using flamable and volatile chemicals. Actually smells much less than traditional SG. Rinsed multiple times after done with regular H2O, then distilled H2O and blew out with compressed air. Was shiny as new after a day of soaking and rinsing. Worked wonders on the cam gears, and all other varnished parts.

Steve