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Rotax Max 125cc Jetting PDF  | Print |  E-mail
Written by Vic R   

For Rotax Evo, use one of the phone apps.

Below is jetting for a Rotax Max. 

CLick on the following diagram for a high resolution version.  





Decrease Jet Size by one size (e.g. 170 - 168) for every increase in elevation of 400m.

Circlip position has a slight impact on Jet size.  e.g. Position #4 is slightly leaner than Position #1

Humidity has a small effect. E.g. Change of humidity from 0% to 100% requires a 0.7 smaller jet size

The Jet # actually is the inside diameter of the Jet divided by 100 (mm).

Other things that may have an impact on jetting -

  • needle size (e.g. k27 or k98)
  • venturi size (e.g. 8.5 or 12.5)
  • Idle Jet (30 or 60)
  • Idle Jet Emeulsion Tube (30 or 60)
  • Float size (e.g. 5.2grams or 3.6grams)
  • Is carby blueprinte?