When using the Allen 418H or 421H on a steep slope, there is a trick that I have learned from mechanics and superintendents that will help extend the life of the engine. This is going to sound a little odd, but try using two-stroke fuel in the Honda GCV-160 engine. Here is why this helps:
The GCV-160 engine, when used on a hover mower, is placed backwards so the spark plug faces the operator. This is done so that when the mower starts down a slope, the oil runs into the main sump area and keeps the crankshaft etc. lubricated. Honda uses a cup and dipper splashing system (an oil slinger) to keep the other parts of the engine coated. When the hover mower is at 45 degrees of slant or less, everything works as intended. However, when the mower is used at an angle steeper than 45 degrees, the oil in the main sump area can actually swamp the slinger causing a lack of lubrication around the top of the engine. By using a mixed fuel, the additional lubrication provided will usually protect the valves and other parts.
One very important note, choose a light mix and synthetic mix for best results. I have used Stihl Ultra at 50:1 and it works well. I have also heard that Amzoil at 100:1 is a good mix too. The synthetic mix burns clean and does not foul the plug. I want to stress that this has not been approved by Honda so they aren’t on board with this tip. But I have heard from techs from around the country that this has helped solve the problem of losing engines when using these machines on steep slopes.