The pinion gear you had on the original motor was a 10 tooth and you now have a 9 tooth gear which will speed up the rotor blades. The 9 tooth pinion is made for the sim blades but will speed up the RPMs of the flat blades if you are using them and that is not a problem. That is the noise you are hearing (increased RPM). You will then be ready for the sim blades.
oppie