RENNtech logo NEW small v2b

Aixro XF-40 Rotary Aviation Engine

Aixro XF-40 Rotary Aviation Engine
SKU: Karting:9900200
Retail price without tax: $6,880.00

The Aixro XF40 combines the performance and power-to-weight ratio of a two-stroke engine with the torque and reliability of a four-stroke engine. Its design is based on the extremely robust Aixro XR50, and it has been optimized for endurance use. The engine has high-temperature ball and roller bearings to further improve its excellent emergency running properties, additional vents allow almost unidirectional mounting, and the auto ventilated V-belt pulley keeps the drive belt cool. Furthermore the XF40's PVL ignition offers variable timing and the spark quality of a battery ignition without needing a permanent battery connection, and its dual intake is equipped with an in-line mechanical unit that ensures full power control.

The Aixro XH40 is identical with the XF40, but it is equipped with a centrifugal clutch inside the output belt pulley. It decouples the engine from the drivetrain in the engine starting phase, which makes it particularly interesting for applications such as manned and unmanned helicopters.

Technical Specifications:

  • Type: 4-stroke single rotor rotary engine
  • Power: 35Hp @ 6500 RPM
  • Weight: 41.2 Lbs (without radiator and exhaust)
  • Torque: Exceeding 26 Lb/Ft from 4500 RPM
  • Max RPM: 7000
  • Ignition: PVL Fire 650
  • Starter: Push button electric start (battery not included)
  • Output: V-belt pulley (Ø59mm, 16 stripes PJ)
  • Clutch: Optional centrifugal flywheel clutch (XH40 option)


  • Mechanical single-cable dual intake control
  • High Temperature Bearings
  • Bing Float carburetor with fuel pump
  • Standard Apex Seals
  • Air Filter
  • Water channel vents for upside-down mount
  • Onboard starter
  • Pulley for Poly-V Belt (16 stripes, PJ Profile) with internal cooling
  • Ignition with start support
  • 50W alternator
  • auto-ventilated V-belt pulley
  • Stainless Steel 3 Piece Exhaust w/ 90° Pipe, Manifold, Silencer and Springs


  • Centrifugal Clutch for Belt Drive: Add $408.24
  • Aixro Battery Ignition with CDI (170 watt): Add $975.00 No longer Available
  • Wiring Harness for Ignition and Starter: Add $78.62  No longer Available
  • Reduction Drive (2.5:1) w/ Engine Mount Plate: Add $895.00
  • Reduction Drive Belt (Micro V-belt) Add $37.25


Complete CAD Data can be found by following this link:

Download Owners Manual, Parts List and Warranty PDF from our Support site:

Looking to purchase? Contact one of our authorized dealers:

The differences from the karting engine are as follows:

  • Bearings: The bearings used are bearings with more robust temperature-resistant cages. These bearings work fine at the engine speeds the XF40 operates to ensure it to avoid any temperature issues.
  • Water Pump: A karting water pump driven by a toothed belt is attached to the engine. It can be mounted in two different positions, so the outlet can always point upwards (important to avoid air in the pump).
  • Housing Vents: The trochoid housing as well as the two side plates are equipped with connectors for 6mm tubes. These allows air to escape from the water channels when mounted “feet up”, as air bubbles inside the engine could lead to insufficient cooling.
  • V-Belt Pulley: On the first engines the V-belt pulley replaced the central nut on the ignition side. Due to heat issues with some belt types this has been changed, and the pulley is now auto-ventilated and attached with 4xM8 screws to the balance weight. The balance weight itself has been re-designed as the ignition magnet is not required any more.
  • Ignition: The ignition is now located on the “clutch side” of the XR50. We have two different ignitions available, which partly use the same components (rotor is the same, stator is very similar). The first ignition available is a magneto type system, but with a CDI to vary ignition timing and a start supply, which allows the ignition to take power off the battery to produce a spark in the starting phase. The second ignition is a battery system as used in automotive applications. Both ignitions work well, idle well and start well. Each ignition has advantages and disadvantages, so we chose to offer both:
  • The battery system has a stronger spark at lower rpm and produces a higher generator current (170W). The disadvantage of this system is that it has to be permanently connected to a working battery, which can be seen as a potential risk by some aviation customers. The magneto-based system will run without a battery, but has a slightly less intense spark at low rpm and only supplies 50W generator output.
  • Carburettor: We have chosen to use the Bing carb with the K&N air filter as this has proved to be very robust.
  • Intake: Controlling the direct intake with the vacuum actuator was a problem for some customers. Also the vacuum actuator sometimes opened before needed thus increasing the main bearing temperature more than necessary. Thishas been replaced with a mechanical device which is mounted in line with the throttle cable and opens the direct intake on the last quarter of the carburettor opening.


Contact us

7825 SW Ellipse Way, Stuart, FL 34997
(+1) 561 - 845 7888
Mon - Fri 9am - 6pm


© 2017 RENNtech, Inc. All Rights Reserved.
7825 SW Ellipse Way - Stuart, FL 34997
TEL: 561.845.7888 FAX: 561.845.6777 E-MAIL: