i have a yz400f and when you switch gears it doesnt feel like it changes but it does. but the shifter feels like it didnt catch the gear? and i was alos wondering what all is interchangeable on the 426,400, and 450 will the top ends bolt on to my bottom end. i am using a dr.d wet sump how much oil should i use 1 quart? and if the 426 or the 450 top end will bolt on my 400f can i still use my dr.d wet sump?