Emission Control System - Honda Nighthawk CB 750 1991 Service Manual

General Information
Emission Control System
The U .S. Environmental Protection Agency and California Air Resources Board (CARE) require manufacturers to certify that
the~r motorcycles comply with applicable exhaust emissions standard during their useful life, when operated and maintained
-
according totheinstructionsprovided, and that motorcyclesbuilt afterJanuary 1. 1983complyw1thapplicableno1seemission
standardsfor 1 yearor 6,000 km (3.730 miles) afterthe timeof sale tothe ultimate purchaser. when operated and maintained
according to the instructions provided. Compliance with the terms of the Distributor's Warranties for Honda Motorcycle
Emission Control Systems is necessary in order to keep the emissions system warranty in effect.
Source Of Emissions
The combustion process produces carbon monoxide and hydrocarbons. Control of hydrocarbons is very important because,
under certain conditions, they reactto form photochemical smog when subjected to sunlight. Carbon monoxide does not react
in the same way, but
it
is toxic.
Honda Motor Co., Ltd
.
utilizes lean carburetor settings as well as other systems, to reduce carbon monoxide and
hydrocarbons.
Crankcase Emission Control System
The crankcase emission control system routes crankcase emission through the air cleaner and into the combustion chamber.
Condensed crankcase vapors are accumulated in the drain tube which must be emptied periodically. Refer to the Maintenance
Schedule (page 3-4). The drain tube needs to be checked for oil accumlation more frequently if the machine has been
consistently ridden at high speeds or in rain.
AIR CLEANER
*(3) : BLOW-BY GAS
*(4) : FRESH AIR