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Mini Max "Squish Gap"


United States Rotax Max Challenge

Technical Bulletin 2013-09

IMPLEMENTATION: January 1st, 2014

Modified Regulations – Squish Gap – Inlet System:
Technical Regulations 2013 – Appendix for 125 Mini MAX - United States

1. Page 1, section 9.10.1 – Squish gap Minimum 2,80 mm

To achieve the defined squish gap, a spacer (ROTAX part no.626 420, same shape as a cylinder base gasket) plus the different required base gaskets must be used. The squish gap must be measured with a certified slide gauge and by using a 3 mm tin wire. The crankshaft must be turned by hand slowly over TDC (top dead center) to squeeze the tin wire. Recommended 3 mm tin wire (ROTAX part no. 580 132). The squish gap must be measured on the left and right side in the direction of the piston pin. The average value of the two measurements counts.

2. Page 1, Section 9.10.2 – Inlet system

The gap between the two reed petal stoppers must be of a minimum of 20.5 mm in any place between the two stoppers and must be evenly spaced to the center of the reed cage, as shown in the illustration. The stoppers must be of original curvature and shape.

3. Carburetor configuration

The specific configuration for the Mini-MAX class is:

  • Only floats marked 3.6 gr or 5.2 gr are allowed. Must be used in matched pairs.
  • Only idle jets stamped 30 or 60 are allowed.
  • Only idle emulsion tubes stamped 30 or 60 are allowed.
  • It is not mandatory that idle emulsion tube and idle jet show the same size.

Squish Gap technical bulletinDownload a PDF version
of the Mini MAX Squish Gap
bulletin HERE.

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