I always have had good luck with Blue Max motors also. But in fairness, there is no other choice. This little chainsaw is a Powerhouse. I haven't used my 20 saw since I got it. Starts on the second pull every time.
Blue Max 8901 Features & Specs
45 cc high performance blue max engine, 35-percent higher performance than alternative brands
30-percent more chain teeth reduces cutting time; anti vibe handle; center balanced.25:1 fuel mixture