The on-line manual is just for the GXV140 engine, not the mower frame. I do not have a manual for your mower, but the usual process is to use specified values where they feature in the manual, and default values elsewhere. I have looked in the HR214 manual and no torque is specified for the engine attaching bolts. Here are Honda's torque values for that mower, including the default values, for each size of bolt:

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I suggest you measure the diameter of the bolts, and look up in the above table, the default torque value for that size of bolt. It will most likely apply, and should do no harm. You will find that in general, when the bolt is screwed into aluminium with a thread length exceeding twice the diameter of the bolt, the specified torque is higher than the default value.