The Yuminashi Hyper Oil Pump is the highest volume oil pump on the market, and such a high output fuel pump is certainly not a luxury in the horizontal air cooled engines, but really something which you should consider to buy because the much larger amount of oil circulating, takes the heat much faster away from the cylinder head and all other hot running parts, which is typical for this engine type.

This is a great upgrade and cheap insurance.  ** Requires top end removal for installation ***