How would i make a model rotate 90 degrees to the right?

How would i make a model rotate 90 degrees to the right when i press r.
here is what i have already:

PlayerMouse.KeyDown:connect(function(key)
    if key == "r" then
        if Clone.MovedValue.Value == false then
            local model = Clone.Model
            model.PrimaryPart = model.Center1
            local cframe = model.PrimaryPart.CFrame -- Current CFrame
            model:SetPrimaryPartCFrame(cframe * CFrame.new(0, math.rad(90), 0))
        end
    end
end)

So far it moves it up and doesn't rotate.