I heard some old-timers say that they mix a teaspoon of baking soda in the oil before storing their bikes for the winter because it neutralizes acids in the crankcase. Sounds like common sense - but will baking soda hurt the engine when run with the baking soda in it, or does the baking soda dissolve in the oil?
Hey Gyro...don't do it!!!
All engine oils (assuming a reputable manufacturer) already contain sufficient base components to nuetralize acids. If you look up a product data sheet, you will see a number for TBN (Total Base Number), this is a measure of the reserve alkalinity of the oil. Acids are generally formed when the sulphur in the fuel combines with Hydrogen and Oxygen during combustion, and some of it will make in into the engine oil. Since gasolines generally are very low in sulphur compounds, you don't need a super high TBN in gasoline engine oils. Diesel oils have been typically much higher, but TBN's are coming down in them also, as sulphur is removed from the fuel. However, this is one of the reasons that it is better to change you engine oil in the fall before storage, as you remove the acids with the old engine oil. Fresh oil won't have any acids (other than those blended in as part of the ad-pak) as well as no soot or sludge/varnish type residual components.
Anyway, just change your oil in the fall, DON'T add bakinig soda, (or anything else).