Tried that using my boat vacuum pump system, but couldnt get all the old oil out. The new Rocket uses a dry sump and retains much of its oil in an internal tank
and doesnt drain down fully to the pan like a wet sump bike does. I threw out the hex drain plugs and replaced them with magnetic drain plugs with a regular bolt head.
The size is 14x1.5
Much easier to remove the plugs now with a wrench instead of the hex wrench. Dont know if they will catch much on the magnets, but will post a pic. at my next oil change
of all three magnetic plugs to show how much if any is caught. All wet sump engines use multiple drain plugs to get all the oil out of the galleries..
My Z-51 C-7 Corvette has two drain plugs that use the same size plugs as the Rocket. DId magnets on those two also. Engines that share the clutch, drivetrain gears, and engine
with the same oil are much tougher on oil because of shearing than a regular car engine, or a Harley.