Designed as a replacement for the long established Max 61FX, the new Max 65AX has all the features of the new AX series, such the same mounting bolt pattern and silencer bolt dimensions, making a direct replacement for most 61 class engines. The real bonus is more power and torque for the same basic external dimensions. Like all the AX series, cooling has been improved by the use of deep finning on the crankcase and cylinder head combined with the new fin pack shape. The silencer is effective and a great benefit to flying fields with sensitive noise issues. Effective silencing is very much part of the AX design philosophy. Carburation is the usual OS 'exemplary' standard and very much why OS engines are regarded as the best! That comes from careful design and testing allied to stringent manufacturing standards.