I ran (6) 9 oz tanks through my GS-40 before it was ready to fly, and it took another 1-1/2 gallons to fully break in. I've run over 6 gallons through it and it think its now running stronger than ever. It also hand starts on the first or second flip like clockwork. One of the best engines I've had, and one of the most reliable also.

Hogflyer