For one thing, their engines are automotive (car) engines that have been re-purposed to power your aircraft. Secondly – they do not pretend to know more about building engines than the people at Honda or Mitsubishi.
Viking take one of the most reliable and high-tech engines on the market. They add a gear box, some engine mounts and a custom ECU and then ship it to you.
As a result you get the same reliability, efficiency and value that we have enjoyed from Honda and Mitsubishi for decades. Viking engines do not over-heat any more than a new car does. They are no more likely to stop than your car engine and they take nothing more than a throttle and key starter to operate.
No carburetor – so no carby heat or carby icing. Fuel injection and computer-controlled mixture – so no primer, no choke, no mixture controls and no looking for lean-of-peak.
Parts are available pretty much anywhere, premium unleaded fuel is all you need and expertise is available from every service center.