1984 125m no 4th gear need some help

[shdtreemechanic]

I just got a 84 125m I know these have granny problems but I haven't seen anything like this before this bike shifts down into 1 2 and ers gears but when you hit 4th it's in neutral again is like to k nsow that someone else had had this problem and if so someone please give me some info thanks in advance

[shortline10]

Sounds like the typical shift drum stopper issue to me , probably going In between 3rd and 4th gear , which will act like its in neutral.
Remove the clutch cover an inspect .