No you do not have to drill holes in your aluminum clutch cover. Read the instructions and it should be clear about using the T-nuts that should be attached to the back of the plastic clutch cover. The plastic clutch cover is then glued onto the aluminum clutch cover and then the chain guard will be attached by screwing it onto the T-nuts. Here are the instructions out of the manual
Chain guard fabrication and installation
1. Print a copy of the clutch cover plate and chain guard template found on the
2. Using the supplied black plastic material cut out the two pieces using the
template as a guide with a knife or tin snips.
3. Drill 13/64 inch holes as marked on the templates.
4. Test fit the two pieces on your engine ensuring that when the 3 holes line up,
the chain guard is protecting the small sprocket.
5. Insert the 3 T-nuts into the back side of the plastic clutch cover plate using a
hammer to get them as flush as possible.
6. Clean your clutch cover with brake clean or rubbing alcohol to remove any
oil or grease.
7. Apply a thin coat of contact cement to the engine clutch cover and the
backside of the plastic clutch cover plate. The backside is the one with the
large portion of the T- nuts showing.
8. Allow the contact cement to set up according to the manufactures instruction
and place it on the clutch cover.
9. Install the chain guard by screwing it to the T-nuts on the plastic clutch cover plate.