Hey guy clik on lt500r go to 87-90 engine changes and all proper stock carb info is there because internal part changes were made 87-90 and it also tells Carb# s and what 1 fits the year 1 u have and the proper jets an internal parts that shld be in it. If u buy an eBay carb contact seller an ask him what numbers on the top square pad on the intake side of the Carb . The top # s the main # u need to no.