The 131″ Screamin’ Eagle Stage IV is the new high-end kit to increase the performance of Milwaukee Eight engines. According to the manufacturer’s specifications, it develops 123hp of power and 178 N-m of torque measured at the wheel.

All this on paper, but in real life is such a monster engine drivable? Is it suitable for road use?

Those who will continue reading will find the answer in this short article.

Milwaukee Eight StageIV 131

The main components of the 131″ Stage IV are:

  • CNC machined cylinder heads with performance valve springs
  • 64mm throttle body
  • 5.5g/s high-flow injectors
  • 4.075″ Bolt-On cylinders
  • Aluminium coated, forged, high compression pistons
  • SE8-517 Cam
  • High-performance tappets
  • High-flow catalytic headers and Euro 4 Screamin’ Eagle Street Cannon slip-on with DB killers.

The stage was installed by an H-D dealer, while both the map for the first ignition and break-in and the subsequent tuning were provided by our Tuning Center. The tuning was done on a DynoJet dynamometer with Power Vision.

The Road Glide arrived at the Tuning Center from the beautiful city of Parma at the end of the break-in period during which it used a map that had been developed with the Remote Tuning Service.

The first impression was very positive: deep and compact sound, low mechanical noises and ticking. I can say without fear of contradiction that the excellent impression and the beautiful sound are due not only to Stage IV, but also to the professional installation job carried out by the H-D dealer.

In the graph below you will find the numbers of both the map made for the first start-up and break-in and the map obtained at the end of the tuning.

What you won’t find on the graph is that the bike is also very smooth and rideable, so much so that it is tempting to use it on a daily basis.

Torque is expressed in N-m