Co Concentration (Mixture Adjustment) - Toro Workman 3000 Series Service Manual

CO Concentration (Mixture Adjustment)

1. Make sure engine is warm (coolant temperature 80 –
95�C (176 – 203�F), all lights and accessories are OFF
and transmission is in NEUTRAL.
2. Check to make sure that idle speed and ignition timing
are the standard values(see Idle Speed and Ignition
Timing in this section).
Standard values
Idle speed
Ignition timing
3. Check CO and HC concentration for standard values.
Standard values
CO concentration
HC concentration
Note: There are two types of carburetors which can
be installed on the liquid cooled gas engine. One is
marked TMB, which can be adjusted by the customer.
The other is marked TEB, which is U.S. Environmental
Protection Agency (EPA) and California Air Re­
sources Board (CARB) certified and must be adjusted
by the manufacturer or your Mitsubishi/Toro Distributor.
4. On carburetors with identification mark TMB:
A. If concentrations are outside the standard value,
use the mixture adjusting screw (MAS) to adjust the
CO concentration.
B. After running the engine at 2000 to 3000 RPM for
15 seconds, check CO concentration again. Use
MAS screw to adjust if necessary.
C. If test equipment is not available, turn MAS
clockwise until engine begins to idle roughly, then
turn counterclockwise 1 turn.
Workman 3000/4000 Series
1200 + 100 RPM
6� BTDC + 2�
1.0 + 0.8%
800 ppm or less
Page 3 – 21 Rev. B
MAS
Figure 29
IMPORTANT:All carburetors with a TEB identifica­
tion mark have a tamper–resistant idle Mixture Ad­
justing Screw (MAS). The CO setting has been done
at the factory. Do not attempt to adjust the MAS, this
will be in violation of U.S. Environmental Protection
Agency (EPA) and California Air Resources Board
(CARB) regulations.
5. On carburetors with identification mark TEB: If
concentrations are outside the standard value, replace
the carburetor.
Liquid Cooled Gas Engine