I have a Twister z150r with external reverse that wont engage - checked linkage to be sure it was woking, pulled gearbox apart and cleaned old grease and gunk out -shifter fork wasnt moving full travel with gunk behind it- cleaned and got full tavel with shift lever-put it back together -still wont go in reverse sets there in neutral while rev up engine (GY6) all gears looked good with no wear--HEELLPP!
