Mad,

I'm not familiar with the Goldberg Yak but get in touch with Aerobob. I know he has one and a very limited report on it on his web site

http://www.rcaerobats.net/CG-Yak/Yak_Main.htm

Also, for break in 2 gallons is not near enough for almost all gas engines. DA and DL recommend at least 5 gallons and Fuji and 3W go by time which for most people will be about 5 gallons.

My standard breakin for all gas engines is 5 gallons on either Lawnboy ashless or Pennzoil air cooled, bioth at 32:1 then a good synthetic and whatever the oil manufacturer says to use.

I've got 2 DA50's both with well over 20 gallons, one Da150 I'm jsut starting on and 2 Fuji 43cc engines, a couple of Ralph Cunninghams converted g-26's, 3 3w engines in various sizes from 55 to 80cc and all have been broken in the exact same way and all are very reliable.