Can any one tell me how the height of the 30mm HRC stacks are measured?
Is it 30mm from the airbox tray or from the mouth of the carb?

I think its the physical lenght of the velocity stack

30mm is the height that it sits above the carb, not the whole stack length.

Cammo wrote:30mm is the height that it sits above the carb, not the whole stack length.

As I thought,it's the amount it protrudes into the airbox, thanks.

Do yo have some, are you get some made ??

999Gomerz wrote:Do yo have some, are you get some made ??

Rick oliver already sells replica short stacks.


Never truly understood how exactly they work though

Most modern bikes have two piece split stacks connected to a steper motor that lift up away from the throttle bodies after a set rpm , long stacks help produce power at lower rpm, short stacks produce power at high rpm.

amaechizzle wrote:

999Gomerz wrote:Do yo have some, are you get some made ??

Rick oliver already sells replica short stacks.


Never truly understood how exactly they work though

but I read in his parts list that he says they are 20mm not 30mm like the HRC ones, I was meaning are you getting 30mm ones made like the original HRC ones.

I reckon the cost would of getting them made would outweigh the benefit.