The HX-12A has been developed to further improve the performance of the Rotax engines. The larger 30mm venturi model has become extremely popular in Rotax Open categories where the performance is much improved over the stock carburetor.

Venturi: 30 mm

Throttle Bore: 34 mm

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

Suitable for open racing where rules permit use of any carburettor.  Not permitted in Rotax World,  Rotax Max Challenge and other unmodified Rotax-sponsored racing.  Check your local rules for permissions.

Recommended Initial 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 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


Setup Guidelines: 

1) Mount the carburettor to engine

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

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

4) Draw the fuel to the carburettor

5) Cover the air filter trumpets by hand and turn over engine until it fires / or remove air filter and cover choke the carburettor inlet by hand and start engine

6) Go Racing!!


Repair Kit and Diaphragm Gasket for this carburetor:

Main: RK2-HW and DG2-HW

Optional: RK1-HW and DG1-HW

Weight1 kg
Venturi Diameter


Throttle Bore Diameter


Venturi Range

Throttle Bore Range

Racing Class

Product Line