Question about FCR velocity stacks

Discussion in 'WERA Vintage' started by crashman, Jan 1, 2019.

  1. crashman

    crashman Getting slower every day

    I need to get a set of velocity stacks for FCR's to put on an 86 GSXR1100 Superbike motor. Short stacks give better top end and long stacks give more torque, correct?
  2. Kurlon

    Kurlon Well-Known Member

    Kinda, sorta? You choose the stack length based on total intake tract length, desired RPM and cam. You may NEED a longer stack just to make your setup work depending on how the variables play out?
  3. crashman

    crashman Getting slower every day

    Thanks. I have always run the bike with 38mm Mikuni RS's and 50 mm stacks but have never messed with stack length and have no experiencer at all with the FCR39's. It is making enough torque down low that I can afford to give a bit up if it gives me more on the top end. I am torn between going with the 50mm's that I know worked with the Mikunis or going with the 35's to try to squeeze a bit more top end out of the old girl...

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