I need a manual for my elnita 250 by elna. It hasn't been used in 20 years so I want to make sure i'm maintaining it properly before I use it.

There are a few things I would recommend; get some Marvel mystery oil, remove spark plug and fill cylinder with the marvel. allow to sit at least overnight before draining and pull the starter a couple times to free up the piston rings. While you are waiting, remove the carb and fuel tank - flush both with starting fluid first then fresh fuel. If you are familiar with carburetors and air / fuel jets, count the turns on each respectively to bottom then remove. Soak in starting fluid for at least an hour and flush out respective ports with starting fluid then carb cleaner then fresh fuel. Use non - lubricated starting fluid as you want the highest concentration of Ether to break loose the varnished fuel.Flush out fuel lines and primer bubble ( if equipped) with fresh fuel and spark plug out. You can best do this by re - installing fuel tank and filling with fresh mixed fuel, adding the fuel stabilizer at double the recommended strength - this will not harm the motor, just help it start and stay running. Place an air hose blow nozzle in the mouth of the tank, wrap with a clean rag and gently blast air into the tank until 1/4 of fuel in tank has passed through. Cap tank and turn saw over to drain the fuel out of the cylinder, giving it at least 10 minutes to drain. Now replace spark plug and follow starting procedures - you should have it running strong now!! If it refuses to start or sputter in the first 5 pulls, remove spark plug and shoot a 2 second blast of lubricated starting fluid into the cylinder. Install plug and start. You may have varnish issues due to the lengthy storage time and you may be better served by getting a rebuild kit for the carb and rebuilding it or even replacing carb. Fortunately 2 stroke carbs are much easier to rebuild than a 4 stroke.
Good luck!!!