manual ATV help?

[James B]

OK so when ever i'm driving my yamaha warrior (1994) i try to change the gears while im still moving i pull the clutch in and pop the gear up and let the clutch go slowly but every time a do that i get this put put put put put noise like its going to stall and it really doesnt feel normal because its never done that before should i completely stop before changing gears or should i just leave it only but i get this feeling theirs a problem with the transmission or just i should completely stop before switching gears.
I do push the gas some to while releasing the clutch