My 1987 K5 has been jumping out of 4th gear ever since I got it. Ive only ridden it about 5 times,and usually never get out of 3rd with it,but when I do shift to 4th under a load,it will go into fourth,then jump back down into 3rd. If im being ginger with it,and don't have it under too much of a load,it will stay in 4th. The tranny has always been kinda "notchy" and hard to shift,but it does shift and run fine in 1st,2nd,3rd,and 5th....only 4th gear has this issue. Could this be a problem with the shifter mechanism on the shift drum,..or most likely a thrust washer or gear/shift fork issue?? Please,...give me some insight/suggestions.....
Thanks!!