Chain Tension; Chain Oiler; Chain Maintenance - Ryobi APR04A Operator's Manual

 Remove all slack from chain by turning the chain tension-
ing screw clockwise, assuring that the chain seats into the
bar groove during tensioning.
 Lift the tip of the bar up to check for sag. Release the tip
of the bar, and turn the chain tensioning screw 1/2 turn
clockwise. Repeat this process until sag does not exist.
 Hold the tip of the bar up and tighten the bar nut
securely.
 Chain is correctly tensioned when there is no slack on
the underside of the bar and the chain is snug, but can
be turned by hand without binding.
NOTE: If chain is too tight, it will not rotate. Loosen the bar
nut slightly and turn adjusting screw 1/4 turn counterclock-
wise. Lift the tip of the bar up and retighten bar nut.
WARNING:
Check the chain tension frequently when operating the
unit. Never touch or adjust the chain while the engine is
running. The chain is very sharp; always wear protective
gloves when performing maintenance to the chain.
TRIMMER ENGINE IdLE SPEEd
AdJUSTMENT
If the chain turns at idle, the idle speed screw needs ad-
justing on your trimmer engine. Turn the idle speed screw
counterclockwise to reduce the idle RPM and stop the chain
movement. If the chain still moves at idle speed, contact a
service dealer for adjustment and discontinue use until the
repair is made.
WARNING:
The chain should never turn at idle. Turn the idle speed
screw counterclockwise to reduce the idle RPM and stop
the chain, or contact a service dealer for adjustment and
discontinue use until the repair is made. Serious personal
injury may result from the chain turning at idle.

chAIN TENSION

See Figures 16 - 17.
 Stop the engine before setting the chain tension. Discon-
nect the spark plug wire and/or ensure that the engine cut
off switch remains in the off position before any adjust-
ments are made. Make sure the guide bar nut is loose to
finger tight, turn the chain tensioning screw clockwise to
tension the chain. Refer to Replacing the Bar and chain
for additional information.
A cold chain is correctly tensioned when there is no slack
on the underside of the guide bar and the chain is snug,
but can be turned by hand without binding.
 The chain must be re-tensioned whenever the flats on
the drive links hang out of the bar groove.
MAINTENANcE
 During normal operation, the temperature of the chain will
increase. The drive links of a correctly tensioned warm
chain will hang approximately .050 in. (1.25 mm) out of
the bar groove.
NOTE: New chains tend to stretch; check chain tension
frequently and tension as required.
cAUTION:
A chain tensioned while warm may be too tight upon cool-
ing. Check the "cold tension" before next use.

chAIN OILER

See Figure 18.
 Use Premium Bar and Chain Lubricant. It is designed for
chains and chain oilers and is formulated to perform over
a wide temperature range with no dilution required.
 Remove the cap and carefully pour approximately 235ml.
of the bar and chain lubricant into the chain oiler tank.
 Replace the cap and tighten securely.
 Check and refill the chain oiler tank every time the engine
is fueled.
NOTE: Do not use dirty, used, or otherwise contaminated
lubricants. Damage may occur to the oil pump, bar, or
chain.

chAIN MAINTENANcE

See Figure 19.
The chain is very sharp; always wear protective gloves
when performing maintenance to the chain.
Use only the replacement low kickback chain specified for
this unit.
For smooth and fast cutting, the chain needs to be maintained
properly. The chain requires sharpening when the wood chips
are small and powdery, the chain must be forced through the
wood during cutting, or the chain cuts to one side. During
maintenance of the chain, consider the following:
 Improper filing angle of the side plate can increase the
risk of a severe kickback.
 Depth gauge (or raker clearance) setting determines the
height the cutter enters the wood and the size of the wood
chip that is removed. Too much clearance increases the
potential for kickback. Too little clearance decreases the
size of the wood chip thus decreasing the chain's cutting
ability.
 If cutter teeth have hit hard objects such as nails and
stones, or have been abraded by mud or sand on the
wood, have a service dealer sharpen the chain.
7
WARNING: