Repair or what?

Luckily water is heavier than gasoline. There is a carb bowl drain as well. Drain a little out of the carb bowl and see if it looks contaminated.

Also, are you using the choke to start it? Try moving it to different positions while starting, and don't stop pedaling. If you still have no luck, take the spark plug off and see if it's wet. And also, how much oil did you premix? Are your coil and kill switch hooked up right?

I received a brand new engine last week, that had 2 base gaskets installed from factory.

I would really examine the engine closely, and look for an obvious flaw.

Check the base gasket, and head gasket, and be certain that everything is o.k.

sometimes a new engine needs the choke to get it to fire just a few times, then it wants no choke to get it to start again - also, be sure the slide is all the way down in the carb

Have you checked to be sure you have spark? These magneto coils can not get wet and will burn out in short order if they do get wet or if water gets under that cover.
Also, what is your plug gap set at? These engines don't have super strong ignitions so running a tighter gap helps, try setting the gap between .024" and .026". This will help most new engines start a lot easier.

The problem is the magneto coil... it does NOT like water, if your having trouble with it starting and it's been sitting out in the rain or if you decided to hose down the bike to wash it, there's a really strong chance it fried the mag coil that's located under the left side cover on the engine, remove that cover and see if there's any water in there, even if it's just condensation I would recommend replacing the mag coil.
A few drops of water in the fuel is nothing compared to letting the mag coil get wet.... and the gasket provided in the kit or installed at the factory doesn't do a very good job at keeping water or moisture out. Even those of us who went in and sealed this area better with gasket sealant and sealing off the opening where the 3 wires come out, we still don't ride in the rain, store the bike where it can get rained on or wash the bike with a hose, but instead store the bike inside, cover with plastic if it has to be outside, and use other methods to keep the bikes clean... all because water KILLS mag coils.
You can drain the carb and the tank and put in some fresh fuel, but if that don't help it start, I'd be looking under that left side cover...