> I have a stuck choke. For those of you who are too young to remember when cars had a choke, it is a little butterfly valve in the carburator that chokes down the air flow to produce a richer mixture of gasoline vapor and air. This makes a cold engine start easier. With fuel injection, you don't need one. This one is stuck open and I've tried WD40, carb cleaner, and penetrating oil and applied some pressure. Nada. Anybody have any more ideas? I also have an aluminum engine with an overtightened spark plug. This usually results in stripped threads and a ruined cylinder head. Any ideas on that one. Fortunately the spark plug is on a spare engine and not the one on the scooter I just bought.
> Howard

I rebuilt an engine last summer that had been sitting outside for over 30 years. The varnish had the whole carb immobile.
Soak it. There are two ways I have done this:

Chem-Strip - Parts stores (like Pep Boys) sells this in gallon cans with dip baskets included. Best to disassemble the carb and put ONLY the part of the body with the choke in the basket. Chem-Strip is NASTY-lookin (and smellin) stuff. The ingredements list all kinds of hazardous chemicals. You dip and soak it for a while, rinse with water, and blow the part dry. CAUTION! Any non-metallic pieces will likely disappear! As Granny Clampett would say, "If they fell in there, they's done deesolved by now!"

Gum-Out - This is my poison of choice for carbs. Probably what you've already used. But here's a variation. Get a can or GLASS jar that you can seal. Spray enough Gum-Out in it to cover the part, and soak the part. Swishing occasionally until thoroughly done. Using an old toothbrush to scrub around the choke's pivot point will help, too. You know to be careful around this stuff, too. That burning, drying sensation you feel in your hands is because Gum-Out is so volatile. When you get the choke freed, set the open container somewhere where the breeze can evaporate the liquid.

As for the plug, is it overtightened, or just seized from being installed for so long?
Take the head off and douse around the plug hole LIBERALLY with Marvel Mystery Oil. Do this a few times a day, letting it soak in. This will help lube an over-tightened one and a seized one.
Put your head in a vise (not yours! the engine's!), use a box-end wrench and a small hammer and peck and peck and peck and peck... (ad infinitum) to see if you can get the plug to budge. Patience is the key. Kind of like cutting stone.
Another thing you can try after the Mystery Oil soak is using a propane torch to heat the plug. Be careful not to get the insulator too hot. It'll shatter. Focus the tip of the flame right where the steel of the plug and the aluminum of the head meet. Heat it up til you think the plug is about operating temperature. Give it a little crank while it's hot. Give it another when it cools off. The different rates of expansion of the two metals will help break it loose.

If these fail and the threads get stripped, it's Heli-Coil time.