If carburetors are adjusted too rich, what will increase in the exhaust?

When carburetors are adjusted too rich, it means that there is an excessive amount of fuel compared to the amount of air entering the combustion chamber. This imbalance leads to incomplete combustion of the fuel, which results in the production of increased levels of hydrocarbons (HC) and carbon monoxide (CO) in the exhaust.

Hydrocarbons are unburned fuel particles that escape the combustion process. When the fuel-air mixture is too rich, not all of the fuel is combusted during the process, and as a result, more HC is released into the exhaust. Similarly, carbon monoxide is a byproduct of incomplete combustion and increases when there is insufficient oxygen to fully combust the available fuel. Therefore, with a rich mixture, the emissions of both hydrocarbons and carbon monoxide will increase significantly.

Other options, such as nitrogen oxides (NOx), typically increase in lean conditions where there is more air than fuel, due to higher combustion temperatures. Ozone levels are affected by atmospheric reactions rather than direct emissions from combustion, and carbon dioxide (CO2) is a product of complete combustion rather than its deficiency, so its levels would not specifically increase due to a rich fuel mixture.