I have read the comments and saw that you did get it to start by spraying gas into the carb. With that, I think you have pretty much eliminated the spark and compression issues and what you are left with is a fuel issue. So you need to determine is fuel flowing from the tank, flowing through the fuel line to the carb, then flowing into the carb. So, I would check things in this order: 1. Get a small tray or cut soda drink bottle to catch fuel. 2. Disconnect the fuel line at the tank and make sure you have a good fuel flow. 2. If you have good flow from the tank, reconnect and then disconnect at the carb and make sure you have good flow through the hose. Sometimes the inner fuel line will deteriorate and the inner hose will get pushed back up into the line when the line is pushed back on the nipple at the tank or carb and block the line. 3. If you have good fuel flow going into the carb, then the issue is the carb. In my opinion, those carbs suck. The jets in it can get clogged and no matter what you do, sometimes they never clear up. But before messing with the jets, put some gas in the tank and allow it to flow to the carb. Then remove the carb and catch the gas in a bowl or pan make sure the carb bowl is full of fuel and that the float is not sticking and the valve is not blocked. 4. If the flow is all good, then you can move on to cleaning the jet. If it still will not start normally but starts when you spray gas into the carb, I would order a new carb because it is cheaper to order the whole carb than just the main jet. You can find the cheap Chinese versions on eBay for 10-12 bucks.