If it started and ran for a bit, timing and spark are good. My guess is fuel shortage. Check your carb first. I had an old suzuki years ago that sat for a while. The float in carb was stuck, corroded pin. Fuel would not fill the bowl so it was always fuel starved. You can also get a cheap carb on Amazon for under $50.
https://www.amazon.com/Carburetor-Suzuki-LT230GE-Quadrunner-1985-1987/dp/B085DJS9X5/ref=pd_lpo_3?pd_rd_i=B085DJS9X5&psc=1