Victa model 500 twin cylinder lawnmower.

[kschauweker]

Introduced in 1975 and only made for a brief period, the opposed twin cylinder engine displaced a modest 170cc. The engine was fueled by Victa's own design 'G4' carburetor. The round discs on the top side of each cylinder barrel are an automatic compression release, used to ease starting effort.
For those unaware, Victa is an Australian manufacturer, and has been in business since all the way back in 1952. Unfortunately, these machines were never (to my knowledge, anyways) sold in the USA.

 

[VolvoZ]

Is that air intake plumbing running up the handle? Likely so that it inhales cleaner air away from the engine…interesting design features. Probably a smooth running motor. Nice.

 

[Slick3914]

Very cool, thanks for sharing!

 

[Arch Stanton]

Is that air intake plumbing running up the handle? Likely so that it inhales cleaner air away from the engine…interesting design features. Probably a smooth running motor. Nice.

That's so you can mow under water. Just like a lot of the off-road 4x4's you see in Australia.

 

[wpod]

I guess the two cylinder is smooth running.

 

[kschauweker]