The HM-2A is a CNC machined carburettor from billet aluminum which has been designed for use on the Rotax engines. Hailed by Vroom! Magazine as the first “proper racing carburetor” for Rotax, the HM-2A posted more than 3/10ths of a second faster lap times vs stock carburetor in independent Vroom! testing.  Read the full article.  The HM-2A and our HX-10A die cast version and larger HX-12A 30mm version offer substantial benefits over the stock Rotax carburetor:

  • Fully adjustable High and Low jet, on track or off-track
  • Butterfly Opening
  • Racing Class Venturi / Body Design
  • Racing Class Inlet Needle and Seat Design
  • Pulse Pump Connection

The  HM-2A, HX-10A and HX-12A are suitable for open racing where rules permit use of any carburetor.  They are not permitted in Rotax World,  Rotax Max Challenge and other unmodified Rotax-sponsored racing.  Check your local rules for permissions.

Recommended Carburetor Settings:

Rotax MAX (Senior/Masters):
L: 1’00”
H: 1’20” – 1’25”

Rotax MAX (Junior):
L: 1’00”
H: 1’15” – 1’20”

Mini MAX:
L: 1’00”
H: 1’10” – 1’15”

Mini MAX:
L: 1’00”
H: 0’50” – 1’00”

L: 1’00”
H: 1’30” – 1’35”

Adjust first the High then the Low needle each in 1-2 minute increments. Find the High setting you like, then adjust Low needle and readjust High then Low as desired.  We recommend using our QuickJet setting tool for accurate setting.  You should not need to adjust more than 10 minutes in normal conditions, but up to 20 minutes in extreme conditions like hot or rainy weather.

Repair Kit and Diaphragm Gasket for this carburetor:
Main: RK2-HW and DG2-HW

Optional: RK1-HW DG1-HW

Setup Guidelines:

 1) Mount the carburetor to engine

2) Connect pulse line to carburetor from crankcase (no need for Mikuni pulse pump)

3) Set the carburetor jets to desired setting, recommend to use the QuickJet tool for accurate setting.  See above recommended settings and adjustment technique.

4) Draw the fuel to the carburetor

5) Turn on the choke pushing the choke lever forward

6) Press start button without applying any throttle

7) When engine starts apply the throttle and this will disengage the choke

8) Go Racing!!!

Additional Requirements and Information:
Can be anodized in custom colors.  Contact for information and pricing.
Special pricing available for Clubs and local racing series.  Contact for details

Weight1 kg
Venturi Diameter


Throttle Bore Diameter


Racing Class

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