Hey guys, my '94 F2 is having trouble starting. When I try to start it, the engine will either just crank or sputter around 200-500 rpms until I release the ignition button. I've only gotten it to start a couple times. Here's some history on the bike:

Bought in November 2017 for $650 (Whoo!)
- When I first purchased it, the bike started right up without trouble and idled well.
I left it sit outside until about late March 2018, which I am extremely regretting now. During this period, I did not start the bike or even touch it.
This month (April) I started working on it again, first
- Replacing the coolant reservoir and flushing out the system due to the reservoir breaking since the P.O. did not use antifreeze.
- Replacing the spark plugs
After I replaced the spark plugs, I poured some gas where I assumed the intake was, just past the carbs. The bike eventually started, and I rode it around for about an hour. I was driving home just after parking it for about an hour, and I tried to lower the idle while the bike was running. The engine died, and I was unable to get it started again, enlisting the help of a random truck owner to tow my bike home.
After this I replaced the oil and cleaned out the carbs. I'm not super sure how to clean the carbs, all I did was take them apart and soak the needles in carb cleaner, blowing them out with compressed air afterwards. I tried to start the bike again after this, but I think I flooded the engine since I decided to give it gas while starting it.

Today, after about a week from cleaning the carbs, I fired the bike up again. It started really quickly and idled without an issue. However, after about 5 minutes I turned it off to get geared up, and when I came back out I was unable to get it started. It just sputtered like before until my battery became too weak. I'm going to charge it up and try again tomorrow, but I'm not sure what else to do to ensure it starts up every time. Once it does get started, it seems to run really well. Any advice? This is my first real bike, so I'm not super experienced with the whole fixing process.