Can anyone tell me what year the GSXR750 went to a shim under bucket valvetrain? I have got a 1991 in my garage that I am working one and it has got an excruciatingly loud valve. If it is a screw and locknut motor i will dig in and adjust it. Shim under bucket......thats a different story. Last year for screw and locknut adjustment was 1990 wasnt it??