Modifications of Harley-Davidson motorcycles

A lot of motorcycles in our workshop have been previously modified, most often in the USA. Unfortunately, these modifications often cause damage or breakdowns. We are able to correct it.

At the stage of modifying (tuning) the motorcycle, we select better quality parts. We check dimensions, assembly fits, we correct the factory condition, and if necessary, we make more accurate measurements.

In the case of more complex modifications, we use a 3D measuring machine, hardness tester, and a measuring microscope.​ We can check every part of the motorcycle very carefully in terms of both geometric, dimensional and material hardness. The measurement accuracy is usually 0.005 millimeters. The accuracy of the hardness measurement is +/- 1 HRC. Then we can modify it on CNC milling machines.

Thanks to our knowledge and experience, we are able to eliminate many shortcomings that arose at the construction or assembly stage while still in the factory. Many components of the engine, clutch or gearbox can be modified.

Additionally, we can list here some modifications regarding Harley's engines:

  • modifications to the lubrication system of Shovelhead, Evolution engines;
  • modifications to the crankshaft main bearings on Twin Cam engines after 2002 and Milwaukee 8;
  • increased cooling in the rear head of the Evolution and Twin Cam engines;
  • geometry measurements and correction of engine block deviations;
  • precise "cylinder grinding" with improved geometry;

Gearbox modifications:

  • strengthening of bearings in 5-speed gearboxes;
  • elimination of backlash and leaks at output and clutch shafts in 5-speed gearboxes;
  • elimination of backlash in the splined connection of the pulley - 5-speed gearboxes before 1994;

Primary gear modifications:

  • changes to facilitate engine start - models before 1994;
  • changes eliminating leaks from the clutch support bearing side;
  • primary gear changes;
  • balancing of clutches;

We start each modification with careful measurements of all cooperating parts to determine what the baseline is and we finish with the measurement to know what we have done and whether we are where we wanted to be. :-)​

We draw experience from the automotive industry, therefore all our activities are based on the principles of the quality management system guiding this industry.