Valach Engines

VM 120 B2-4T

  • 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
  • Nickel-Silicon plated cylinder surfaces
  • CNC milled crankcase
  • Honda Valves
  • Walbro Carburetor
  • Valach microprocessor controlled ignition with auto advance and retard
  • The ignition allows the use of two LiPo cells
  • VM-engines are designed using the latest tools and techniques
  • Rapid spares delivery and repair service from Germany by Toni Clark practical scale GmbH

The VM 120B2-4T is also available with a starter. With the current version of the VM 120B2-4T the starter can be retrofitted anytime

The Valach engines VM 120 B2-4T looks just like an original aero engine, only smaller, it runs smoothly like an original aero engine and above all it sounds like an original aero engine. The designer Zdenek Vlach has produced a real winner, an engine that demanding modellers have been waiting for, for a very long time.

Due to being a four stroke, the low vibration, is nothing but sensational, and torque is really high. The response to the throttle being opened is so smooth without the slightest attempt to surge, making the Valach 120 B2-4T absolutely ideal for your aerobatic model. Being a four stroke with a large capacity produces a very realistic full-size aircraft sound. With a relatively small silencer the sound level is very low rather like a small saloon car.

The Valach VM 120 B2-4T is a four stroke OHV engine with two valves per cylinder, running on petrol/oil mixture. We have tried many oils and recommend Valvoline SynPower 2T oil. Our BEL-RAY H1R, although excellent for two strokes, is not ideal for four strokes, as it burns very well without deposit, therefore not much gets past the piston. With Valvoline Synpower 2T a lot more oil gets through to the crankcase. In Germany we recommend Aral Ultimate 102, as the smell is not so penetrating, it can be stored without deteriorating and it does not contain ethanol! If in your country petrol does not contain any ethanol, you can use any brand you like.

Valves and their seats are manufactured by Honda, ensuring a very high quality. The fully encapsulated valve train reduces sound as well as ensuring the rocker arms are well lubricated.

The cylinder’s nickel-silicon lining is far lighter than conventional steel cylinder liners.

The processer controlled ignition allows easy starting and a exceptionally smooth running in all throttle settings.

The Fiala propellers are very efficient, this being due to minimal blade thickness. They sound especially good on four stroke engines. Ideal Fiala two blade propeller sizes for the VM120: 30×12″, 30×14″ and 32×12″. For aerobatics and glider towing the 30X12″ is ideal. For big and slow flying vintage models, as is with Paolo´s Aeronca C3 and the Fokker EI, the 32×12″ is the best choice

The fuel consumption is approximately 50% compared to that of a two-stroke engine with the same displacement. A 500cc fuel tank lasts for about 15-20 minutes of flying time.



120 cc


47 mm


35 mm

Width including valve covers

310 mm

Length from engine mount to prop hub

185 mm

Engine weight with prop washer and prop bolts

3750 g

with Starter 3930 g

Engine weight with ignition, prop washer and prop bolts

3929 g

with Starter 4120 g

Ignition voltage range

4,8 - 9 V


1:30 - 1:40

Fiala Prop 2-blade


VM 120 B2-4T

More Information

The Valach VM 120B2-4T in the 40% scale Paolo Severin Fokker EI is hidden behind a perfect 80hp Oberursel dummy. Not only does it look much closer to scale, the Valach twin sounds far more realistic than any radial engine could. The full-size Fokker’s flew with the Oberursel on full throttle ticking at only 1100 RPM, so the only way to get that kind of unexcitedly sound in your model is to reduce the cylinder count from seven to two and fly at half throttle at 7/2 times 1100 = 3850 RPM – which the VM 120 happily does, precisely holding any desired RPM all day long.
Please see “Flight testing the Fokker E.I” to fully understand what I mean.

This Y-fitting makes it easy to remove the unwanted oil from the pressure tube of the carburetor. Loop-in the two “branches” into the pressure tube and extend the “trunk” about 6-12 cm to lead it to the lower side of the cowling. Place the Y-fitting underneath the carburetor and the surplus oil will be gathered into the “drainage tube” and can be dumped from time to time, without removing the cowling.

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