Unfortunately the Honda 50cc 4 stroke doesn't appear to have an all-orientation lubrication system like the GX25 and GX35. It's just a straight sump arrangement. Apart from the Stihl 64cc, Shindaiwa make an 80cc four-stroke using their C4 technology that works similar to the Stihl 4-mix. It's used in their high-end backpack blower that costs around $450 to $500 in the US and £450 in the UK. There is an animation of C4 engines at the following site:

http://www.t2500.com/downloads/index.html

I've been toying with the idea of getting a Shindaiwa blower for use as a blower - at least for a couple of years - who knows what might happen during that period that makes me take it apart and do something else with the engine!

Details of the blower: http://www.shindaiwa.com/nam/en/prod...0_eb8510rt.php