There is not much that you have to do when Winterizing a Jet since there is no lower unit oil or seals to freeze.
At a minimum – Sta-bil Marine fuel additive should be used in the fuel tank and the engine run for at least 10 min. By letting the engine run, the entire fuel system will get the value of the stabilization. Fuel tank, lines, carbs and jets in your case (injectors in others). In general with all the corn fuel (ok ethanol) in our gasoline these days, using Sta-bil throughout the year (every other tank) isn’t a bad idea.
If the boat is going to sit for a long term, say 6+ months, then I would fog the engine. In your case, all three carbs just to make sure it sits well. Change or thoroughly clean the spark plugs in the Spring or Summer when you get the boat out.
Other steps:
Wrapping the Engine: Field Mice are notorious for building nests and storing corn, seeds and other food in the jet pump or worse. Since the Exhaust in an outboard jet is exposed through the jet nozzle, mice can climb in and in some cases just build a nest, in other cases if the exhaust port is just right I have seen corn and sunflower seeds on top of the pistons. So wrapping the volute & nozzle with plastic or the entire outboard a small tarp is a great idea.
Cover the Boat: Pull the Drain Plugs and cover the boat. Sun, Rain, Snow, Ice, Leaves, tree limbs and other weather related stuff will add wear to carpets, seats, floors and it is easy to prevent with a boat cover or 20x12 tarp. Cover and Tilt the Trailer so water runs out the back.
Remove Seats, PFD's. Tackle, Electronics (Sonar Displays, Radio face-plates…) isn’t required but it can’t hurt. Storing seats and pfd’s in bins that can be placed in the basement, garage or shed.
Hope that helps. –Chris G.
