Changing tempos of samples without changing the pitch

Hey guys, as the title says I'm having trouble with changing the tempo of a sample. Basically I have a sample that I like and I take the loop and I loop it on recycle before i put in into Maschine. However, I can't seem to get it to sound right if I speed it up on either of them. It makes the samples cut short or cut long or whatever if I try to slow or speed up a sample/ The sample it's self is around 90 lets say I want it to be around 75 how can I do that without changing the pitch of the sample? I have tried time stretching but it makes my sample sound weird and funny afterwards.