Dirt bike won't start after 2 years?

My dirt bike has been in the garage for about 2 years now it started when I last used it. My dirt bike is a honda crf50f and still has gas but I'm notsure if its bad gas

Gasoline starts to go bad in around 1 month unless it is treated with a fuel stabilizer, so the gas in this bike is for sure bad. Drain all the gasoline out and put in fresh gasoline. Remove the carburetor and give it a good cleaning. In the future when you are storing it fill the tank with fresh gas and add a fuel stabilizer like Seafoam. Start the engine and then shut off the fuel supply. Let it run until it runs out of fuel. Remove the spark plug and spray a lubricant into the cylinder. Turn the engine over a few times and then replace the spark plug. It is now ready to store.

After 2 years sitting with gas in it, the carb is all gummed up and needs cleaning.

Because you left gas in it. You'll have to remove the float bowl from the bottom of the carburettor, and remove the jets. Then you'll have to blow air through the jets, and also down the passages the jets where removed from.

With a blocked Jet (Pilot Jet controls starting), it will be very difficult to start and most times won't start at all because no fuel can reach the cylinder.

When you let your bike sit, a little fuel would have sat inside the float bowl and eventually gummed up everything. Always best to put fuel stabilizer into the fuel tank when leaving the bike sit for a while, and drain the carburettor(s).