Any new to you 2 stroke ski should have the entire fuel system overhauled before using it. That is unless the previous owner can provide you proof. So I would replace the fuel lines, fuel strainer, rebuild the carbs with genuine Mikuni carb kits and set the pop off. Replace the little oil injection lines and prime them too. Also, if the old owner gave you oil make sure it's api-tc rated, if not drain the oil for the tank and rv cavity and replace the oil with the correct rated oil. I'd also do a compression test just to get a number on the engines health.