125-200cc gearbox binding up in neutral

hi ive a cr125 04 model and ive noticed that when on the stand if i put it in n and i spin wheel in forward direction the gearbox after one revolution "binds"up and the lever looks like its trying to select 1st,if i spin in reverse then there seems to be no issue??ive just put new sprokets on front n rear.also replaced the spacer, oring and washer n clip,all husky parts and renthal sprokets.any ideas please as id like to get in front of any expensive problem before it rips engine apart,hope you all ok out in husky land and are enjoying your bikes as much as i am
steve