This video featuring actor Don Knots, reflects the humor of the time while providing a little insight into the design & manufacture of the short lived line of McCulloch racing karts. While McCulloch manufactured kart racing motors from 1959 to 1977, they only made karts for a couple years during the boom of kart racing. That boom was quickly followed by a Bust, and many kart manufacturers went out of business, this is when McCulloch stopped making karts. McCulloch kart engines were by far the most popular engines used on all karts at the time, and the engine side of the business remained worth while for McCulloch for many years until a combination of new owners and a drop in sales volume marked the end of an era for McCulloch. The Yamaha KT100 and Briggs & Straton 5hp engines quickly replaced the hole left by McCulloch exit from karting.
The engine Don is holding in the beginning of the video would be an MC6 kart engine, based on the date and what details can actually be seen. McCulloch intentionally did not say what model it was, probably because they were releasing new models about every 6-12 months at the time due to the highly competitive environment.