1998 Yamaha 25hp 4 stroke won't start

[markzolton]

My 1998 25hp 4 strokeYamaha won't start since using it about a month ago. Back then it did give me some trouble starting it but eventually it started and was fine. I'm getting fuel and spark, the gas is clean what could be the problem/ what steps should I follow to resolve this??
The plugs are new todAY and the battery has a full charge.