yes clean your carbs, and check if there are rust inside! and maybe you are missing springs on your carbs because normaly they close on there own! plus i think if your engine reved high when it was cold you might have broken the poor thing!
1st cleaning the carbs cost nothing but you might want to replace the screws with something harder.
2nd strip the chambers to see inside the piston for damage or make a compression test before you do that if you want. you can see also if the RC valve is ok too, wrong positions will also foul your plugs.
3rd go to premix before testing again at least it will protect you if your oil pump is not working well.
hope this helps! and be patient its not like the weather is going to let you go anywhere fo at least a few months.
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