Thank you for contacting the AnswerARMY.
I would ask that you contact your local dealer and ask that they inspect the unit.
If they have any questions or concerns about the running they are welcome to contact the Husqvarna technical service department.
I can not answer the question of normal since I do not know what is causing the sound. It is not uncommon to hear spark knock in this engine because it is such a high compression engine when compared to other products that we produce.
Thank you for contacting the AnswerARMY.
I would ask that you contact your local dealer and ask that they inspect the unit.
If they have any questions or concerns about the running they are welcome to contact the Husqvarna technical service department.
I can not answer the question of normal since I do not know what is causing the sound. It is not uncommon to hear spark knock in this engine because it is such a high compression engine when compared to other products that we produce.