attempt to pull the chain away from the rear sprocket at the back center. If the chain can be lifted to the height of the top of the sprocket teeth on any brand/model, then it is elongated enough to need replacement as soon as feasible and is causing undue wear. For most street-oriented motorcycles, replacement limit is around 1.5mm of play when measured like this (i.e. - being able to pull the chain 1.5mm off the rear center of the rear sprocket).