I went all through this "is my generator big enough" deal. I ended up with a Kubota diesel for my requirements. Take your amps of what you are trying to start and multiply X3. This is what will be required for initial start for what ever you are running. So for a 15amp motor you will need a 45 Amp generator. Maybe you could get away with less but this will ensure longevity of your generator and equipment you are running on it.