Valach VM R5-420

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€4,499.00 €3,718.18

Product Details


Valach VM R5-420 5 cilinder 420cc 4 stroke engine

At Aerobertics we have been a direct Fiala / Valach dealer for years and we are in direct contact with the factory. We also use them in our demo models and as a result we have the necessary knowledge and experience about these engines so that we can offer you the best support.

The Valach Motors VM R5-420 just looks like a real radial engine, only smaller, above all it sounds like a real aero radial engine. Not improperly smooth, like smaller radials. If you have experienced our Aichi Val on an air show you will know what I mean. The absolute scale flight with the marvellous sound from that large capacity radial engine can, if at all possible, only be bettered with a full-size machine.


The big capacity per cylinder, the valve timing and the supplied ring shaped silencer are responsible for the realistic sound on idle and on part load. Like all Valach engines, the response to the throttle being opened is so smooth without the slightest attempt to surge.

Valves and their seats are manufactured by Honda, ensuring a very high quality. Due to the inclined valves, the combustion chamber is shaped more like a hemisphere. This improves the combustion and the engine has a higher performance. In addition the fuel consumption is lower than otherwise. My Aichi has just a 1.5 Liter fuel tank!


The crankcase, cylinders and cylinder heads are cast like with full-size aero engines, which enables a light weight and the VM R5-420 with the casting surface finish has a very realistic appearance. Due to the steel cylinder liners this engine will have a long life.


We have fitted an electric petrol pump, the VM R5-420 is easy to start and in every flying attitude has a reliable petrol feed. After sucking in with choke closed the VM R5-420 starts after the first or second flip.


The processor controlled ignition allows easy starting and a exceptionally smooth running in all throttle settings. The ignition can be operated with a two cell Lipo battery


We had tried many oils, but recommend Valvoline SynPower 2T oil.


We recommend Aral Ultimate 102, as the smell is not so penetrating and it can be stored without  deteriorating. It does not contain any ethanol.

For a good throttle response in all RPM ranges, we recommend the use of an intake RAM tube.


  • Sensational smooth running and high torque
  • Spontaneous throttle response and smooth mid-range transition
  • Extremely low vibration throughout the RPM range because of the four stroke principle
  • Honda valves and valve seats
  • Walbro carburettor.
  • Valach microprocessor battery ignition with automatic advance and retard.
  • two Lipo Cells can be used as ignition battery
  • VM-engines are now being produced with state of the art machines and methods.

  • Cylinder:  5
  • Displacement:  420 cc
  • Output:  ca. 25 hp
  • Bore:  47 mm
  • Stroke:  48.5 mm
  • Diameter:  425 mm
  • Length from engine mount to prop hub:  255 mm
  • Weight:  11.8 kg
  • Ignition voltage range:  6 - 9 V
  • Idle RPM:  800
  • Max RPM:  4500
  • Propeller size: Fiala Prop 2-Blade: 38x24" to 42x20", Fiala Prop 3-Blade: 36x24" to 40x18"


More Information
Manufacturer Valach
Article reference VM004
Cylinder +120cc

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