I have a friend who is wiring his panel to work with his generator (using a transfer switch). The generator is a Yamaha 4000 watt (4600 surge), and the well pump is 1 &1/2 horsepower (around 1200 watts?) My concern is with startup watts; I'm personally unfamiliar with how well pumps run with generators, will this likely work? Or is there no way to tell without hooking it up?

According to this chart, 4 KW generator is too small for a 1.5 HP motor.

Electric Motor Wattage Guide

Thanks for the info, we'll give it a try anyway and see if it works.

I know this is an old post, I just wanted to give an update. We got the generator hooked up and tested it out. (The exact model of the generator is a yamaha EF4600). The economy switch was on at first, which brings the engine RPMs down when there is no load. We turned on the well breaker and the generator quit instantly. We turned the economy switch off on the generator, restarted it, and let it run for a minute, then switched the well back on. It seemed to "struggle" just a little bit, but ran for a short time and built the water pressure back up to normal before the pump shut off. The generator ran fine from then on.
Is there a risk of damaging either the generator or the pump during long term power outages if it is turned on a couple of times a day? It will of course be the only appliance running at the time.
Thanks.

Yes, since it was decided to use a generator that is too small to start a 1.5 HP motor, there is a risk of damaging both.