MTD 61 series, Shop Manual

Page: 66 / 142

61, 65 and 70 Series Vertical Shaft Engines
60
10. Clean the carburetor body in an ultrasonic cleaner.
NOTE: Traditional dips are not recommended.
11. Rinse thoroughly.
12. Dry the carburetor body using compressed air.
13. Pre-installation adjustment:
13a. Tighten the idle speed screw until 1/8” (3 mm)
of the screw is visible on the throttle arm side
of the housing.
14. Reassemble the carburetor and install it with a new
fuel line, by following steps 1-8 in reverse order.
15. Start engine and check the idle RPM using a
tachometer.
NOTE: Idle speed: If applicable, is 1,800 RPM +
160 RPM, set using throttle stop screw.
See Figure 4.55.
• For mower applications, the idle speed is not
normally critical because the operator is not
provided with a throttle control.
16. Check the top no load speed of the engine. See
Figure 4.56.
NOTE: The top no load speed will vary depending
on the application. The specification for it will
be listed in the manual for each application.
17. Adjust the top no-load speed by slightly bending the
bracket that the governor spring connects to. The
bracket is visible under the air filter. See Figure
4.57.
Figure 4.55
Figure 4.56
Digital tachometer confirms safe
operating speed
Figure 4.57
Increase spring tension to
increase engine speed
Decrease spring tension to decrease
engine speed.