Mikuni velocity stacks improve the air flow into the carburetors by smoothing small eddy currents that develop near the intake bells of carburetors, especially during high intake velocity conditions.  This not only increases horsepower by improving combustion, but also increases throttle response and fuel atomization.  Fits all Mikuni RS smoothbore carburetors and other carburetors with 55m intake bell O.D.'s. 

Lengths are available in 15mm, 30mm, 50mm, and 70mm.  Choose your length depending upon your clearances and tuning requirements.  Shorter lengths relate to less restriction and higher RPM power whereas the longer lengths smooth flow more and provide higher low RPM torque characteristics.  Velocity stacks are sold in sets of four and include clamps.