You can but you will ahve to drop down to 2 25w bulbs. If you want to upgrade the startor you can get one on egay for like 120-150 bucks that will bump it up to 75w output. If it was me i would run one 50w light or get 2 good 20-25w lights
Or if you realy want good light, get someone to rewire the stator, float the ground, add a recifer a battery, and run a set of HID lights, they don't really need that much wattage when they are on, but need a nice little kick to get fired up. (or you could just wire in the battery, but you would have to way to charge it on a running bike).