Kathy’s Sportster


Kathy wanted the bike to have more power, due to it’s slow nature as a stock 883, while still maintaining excellent street manners and reliability.

Bike details:


Model: XL883 Iron Sportster
Year: 2011
Horsepower: 42
Torque: 38
Engine capacity: 883cc

Initial changes

This was a 2-step process. Initial modifications were the addition of pipes and heavy breather, along with the TTS module & tune. These changes brought the horsepower figure to 54.48 and increased the torque to 49.77.



  • 1200 Cylinders
  • 1200 High Compression Pistons
  • High Compression Cylinder Heads
  • Medium Lift Cams
  • Vance & Hines Exhaust
  • Screamin Eagle Heavy Breather
  • Clutch Plate kit
  • Racing Clutch
  • TTS Mastertune module
  • Dyno Tune

Other Mods

  • 12” Mini Ape Hangers with appropriate cables for rider comfort
  • Engine guard
  • Various aesthetic accessories

The Results:

Initial results

Horsepower: 93.94
Torque: 79.06

Futher Updates

After riding the bike around for some (very happily) time with these changes, we decided to try a 2-into-1 pipe to see how this would affect the overall power / and also where the power would change in the rev range.

A Thunder header pipe was installed. Whilst the max horsepower figure slightly decreased (92.39hp) the torque increased (82.35lb). See the graph below for comparisons…

Note: In the below graph, the base run was based on after the addition of the heavy breather and pipes

Kathys Sportster dyno results

Upgradtes Continued....

The stock suspension on the XL models leaves a lot to be desired. So we changed this out with Ohlins on the rear (specifically for rider weight), and upgraded the fork springs in the front.


These suspension changes have dramatically increased the handling of the bike. So there’s no more aching back at the end of the day!

Finished bike