Honda HRJ216K2 Manual page 60

Tighten the blade disc holder bolt with a torque wrench. Set a flat
blade screwdriver at the engine's bolt to prevent the blade disc from
turning when tightening the blade disc holder bolt, tighten the blade
disc holder bolt to the specified torque.
Blade disc holder bolt tightening torque:
53.9 N·m (5.5 kgf·m)
6. After installing the blade/blade disc check that it does not interfere
with the housing. If the blade contacts the housing, consult an
authorized Honda servicing dealer.
A bent blade can be the cause of serious personal injury or accident.
If you don't have a torque wrench, have an authorized Honda
servicing dealer tighten the blade setting bolts and the blade disc
holder bolt before you use the mower. If the blade setting bolts and
the blade disc holder bolt are overtightened, they could break. If the
blade setting bolts and the blade disc holder bolt are not tightened
enough, they could loosen or come out. In either case, it would be
possible for the blade to fly off while you are operating the mower.
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