190
Two-Stroke Engines
Copyright Goodheart-Willcox Co., Inc.
throttle trigger, and engage the multifunction
lever. Move the lever up to part choke and make
sure the throttle remains locked, Figure 9-14B.
Then, pull the throttle trigger once and check
to see if the choke automatically sets to the full-
open position, Figure 9-14C.
If an engine has a manual throttle lock,
make sure it works correctly. Squeeze the throt-
tle, move the throttle lock to the correct posi-
tion, release the throttle, and check to see if it
remains in the position set by the throttle lock.
In Figure 9-15, the throttle lock is supposed to
set the trigger at half throttle. When the throttle
trigger is released, the trigger should not release
completely, but should stop halfway open.
If the equipment you are evaluating is a chain
saw, inspect the chain brake. First, make sure
the chain moves freely by pulling the top of the
chain forward. Next, engage the chain brake
by pushing the top handle forward. Attempt to
pull the top of the chain toward the nose of the
bar. With the chain brake engaged, the chain
should not move. See Figure 9-16. Finally,
make sure the chain brake releases. Release the
chain brake and pull the chain on top of the bar
toward the nose to verify the chain brake is no
longer locked.
WARNING
The chain cutters are very sharp. Use correct
hand protection when pulling on the saw chain.
Idle WOT
Throttle held
half open
Throttle lock
Goodheart-Willcox Publisher
Figure 9-15. The throttle lock is holding the throt-
tle half open for the start position.
Goodheart-Willcox Publisher
Figure 9-16. Testing the chain brake. A—When the chain brake is not engaged, you should be able to
pull the chain toward the nose of the bar. B—When the chain brake is engaged, you should not be able
to move the chain. This test verifies the chain brake is working correctly.
Chain should
be movable
Chain brake
released
Chain should
not move
Chain
brake set
A B