An additional benefit to installing the non-vacuum type petcock is the ability to fill the float bowls with fuel without cranking the engine for any extended period as is required with the vacuum type. The flow of fuel can be observed in the clear fuel filter also and it adds extra protection from particulate matter which could foul the carburetors. I personally dislike vacuum petcocks that do not have a prime position and replaced the original on the 650 as one of the first things after acquiring the bike.