What do you mean by infinite jump? Do you mean jumping many times per second like doublejump or triple jump or that he makes infinite huge jumps?If you mean jumping many times per second and you are using a premade template there should be an option in the 2dcharacter in the character movement component on the components panel where you can set the jump velocity which makes it jump higher. Just click on the movement component and on the details panel scroll down to the jump section and the first value is jump velocity, but you shouldnt exceed 8000 cause it jumps very very high. if you wanted something like double jump its a little more difficult. you can override a function. Go to the 2Dsidescrollercharacter and in the my blueprint panel there is the functions section.Move your mouse over the word functions and a dropdownmenu called override appears. Click on it and select CanJump. It opens a function were there are two nodes. The one on the right is the return node with the boolean CanJump set to false. Simply change it to true and there you go. it will jump in mid air, but it will jump every time you hit the jump button, so if you hold it it basically flies.When you release it he falls back down. If you want you can limit this to something like doublejump or anything you like. Not the most effective way but it works. Hope I could help you. 