8.14.8 To adjust the metering lever
The distance between the metering lever and the gasket
surface of the carburetor housing must be 0.55 mm.
Adjust the distance if it is more or less than 0.55 mm.
• Move the end of the metering lever down (A) to
decrease the distance. Move the end of the metering
lever up (B) to increase the distance.
8.14.9 To do a pressure test of the carburetor -
option 1
Always do a pressure test after you repair the
carburetor.
1. Make sure the carburetor is fully assembled.
2. Connect a pressure tester to the carburetor fuel
inlet.
3. Put the carburetor into water.
4. Increase the pressure to 0.2 bar.
5. No leakage is permitted. If a leakage occurs, refer to
Troubleshooting leakage on page 47
.
8.14.10 Troubleshooting leakage
Fault
Cause
Leakage in the diffuser jets The needle
valve
Leakage in the impulse pipe The pump gas-
ket
Leakage in the ventilation hole on the
metering unit
The control
gasket
8.14.11 To do a pressure test of the carburetor -
option 2
1. Block the fuel inlet.
2. Make a 0.2 bar negative pressure to the purge
nipple on the carburetor. No leakage is permitted.
3. If there is a leak, use leakage spray and identify
where the spray is absorbed. Use leakage spray to
show leakages in primary jets, idling needles,
measuring cover gaskets and measuring
diaphragms, and AutoTune
™
gaskets.
8.14.12 Adjustment of the AutoTune unit
Note: The product adjusts automatically and will be fully
adjusted after some minutes of normal operation.
The high speed part is adjusted during loaded operation,
such as cutting and felling.
The idle part is adjusted when you operate the product
at idle speed.
8.15 Fuel tank
8.15.1 To disassemble the fuel tank on model 545
Mark II and 550 XP
®
Mark II
1. Drain the fuel from the tank.
2. Remove the chain brake system. Refer to
To
disassemble the chain brake on page 18
.
3. Remove the guide bar and saw chain.
4. Remove the cylinder cover.
5. Remove the spark plug cap and the spark plug.
6. Remove the air filter.
7. Remove the air filter holder and carburetor. Refer to
To disassemble the carburetor on page 46
.
8. Remove the chain catcher to get access to the
screw of the vibration damping system. Loosen the
screw.
722 - 003 - 26.03.2019 Repair instructions - 47
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