Be careful here, you may be dumping a lot of gas into your cylinders and down the cylinder wall past the ring and into the oil. Washing the oil off the rings and diluting the pan oil are not good things. Bite the bullet and get a carb kit before you end up having to buy an engine rebuild kit. Local parts stores can get those kits in a day.
Before you start the engine, squirt a couple of teaspoons of oil into the spark plug holes, turn the engine over a couple of times to distribute the oil and let it sit like that for a couple of hours. Change the oil.
Sometimes the leaking you initially described is caused by excessive wear of the throttle plate shaft and or the body. Wiggle it up and down and see what you get. If there is a lot of wiggle, you may need to send it out to a rebuilder.
Don