We are constantly working on technical
improvement of our products. For this reason,
technical data, equipment and design are
subject to change without notice. All
specifications and directions in this SERVICE
DATA are based on the latest products
information available at the time of
publication. ECHO SERVICE MANUAL Ord.
No. 403-12 contains lots of information for
servicing these models.
CONTENTS
page
1 SERVICE INFORMATION ............................. 2
2 2 91020Limiter plug toolRemoving and installing plug
PB-655
PB-755
2 CARBURETTOR ADJUSTMENT PROCEDURE
2-1 General adjusting rules
A. Before starting the unit for adjustment, check the following items.
1. The correct spark plug must be clean and properly gapped.
2. The air filter element must be clean and properly installed.
3. The muffler exhaust port must be clear of carbon.
4. The fuel lines, tank vent and fuel filter are in good condition and clear of debris.
5. The fuel is fresh ( > 89 octane : RON ) and properly mixed at 50 : 1 with “ISO L-EGD” or “JASO FC/FD”
2 stroke oil.
6. All blower pipes are installed for proper engine loading.
B. Start and run engine for 3 minutes alternating rpm between WOT for 50 seconds and idle for 10 seconds.
Adjust idle speed screw to 2,600 +/- 200 r/min. If engine does not run correctly after this adjustment,
proceed to the next step 2-2.
IMPORTANT : After adjusting carburettor according to the steps 2-2 and 2-3, the limiter plug(s)
must be installed in Idle and hi speed (H) mixture needle(s) hole(s) to comply with Emission Directive.
SERVICE INFORMATION
7
2-2 Initial idle adjust screw, idle mixture needle and hi speed (H) mixture needle settings
1. Remove plugs from Idle mixture needle hole (A)
and H mixture needle hole (B) using limiter plug
tool (C) as follows.
(1)Put limiter plug tool (C) on limiter plug in mixture
needle hole.
(2)Push and turn limiter plug tool anticlockwise 2
turns into limiter plug slowly.
(3)Pull out limiter plug tool with the limiter plug from
mixture needle hole.
(4)Repeat plug removal procedure for the other
mixture needle.
NOTE : When plug is damaged and left in the hole,
use needle or pin-shaped tool to scrape.
2. Turn hi speed (H) mixture needle (B) clockwise
until lightly seated. And then turn hi speed (H)
mixture needle anticlockwise 3 3/4 turns.
Turn idle mixture needle (A) anticlockwise
completely out until a clicking sound is heard. Then
turn it clockwise 10 turns from the point that the
clicking sound is heard.
3. Turn idle adjust screw (D) clockwise until its head
touches boss (G) as shown Fig 1. Then turn idle
adjust screw (D) anticlockwise 8 turns from the point
as shown Fig 2.
(C)
(A)
(D)
(B)
(1)
(G)
(2)
Fig1
(3)
Fig2
NOTE : Initial carburettor setting (Idle adjust screw, idle and hi speed (H) mixture needles) shown here is
to start the engine after restoration or carburettor change. Idle adjust screw, idle and H mixture needles
turn for designated engine revolution through procedures indicated here may vary. As long as idle and
WOT engine speed is set in given range, the variance would be ignorable.
8
2-3 Adjusting carburettor
SERVICE INFORMATION
PB-655
PB-755
(E)
1. Start engine and warm it up alternating engine
speed between WOT and idle every 10 seconds for
1 minute.
2. Adjust idle mixture needle with 2.5 mm blade
screwdriver (E) to reach maximum engine speed
just before drop off.
3. Set idle speed to 2,800 r/min by turning idle adjust
screw. Engine speed ranges 2,800 +/- 30 r/min after
idle adjust screw adjustment.
4. Turn idle mixture needle anticlockwise to reduce
idle speed 200 to 300 r/min in the range of 2,500 to
2,600 r/min.
NOTE : Engine speed must be allowed to stabilize
a minimum of 20 seconds after each adjustment of
L mixture needle to assure accurate tachometer
readings.
5. Adjust hi speed (H) mixture needle and obtain
maximum WOT engine speed just before lean drop
off using 2.5mm blade screwdriver.
(F)
(C)
6. Turn hi speed (H) mixture needle anticlockwise
to reduce WOT engine speed 10-20 r/min. Minimum
WOT engine speed after adjusting should be over
6,800 r/min.
7. Start engine, and verify engine idle speed ranges
from 2,400 to 2,800 r/min, and WOT engine speed
ranges from 6,800 to 7,300 r/min. When final
adjustment is completed, the engine should idle,
accelerate smoothly, and attain WOT per above
specification.
8. After adjusting carburettor, insert and secure new
plug(s) (F) A259-000000 deep in the needle holes
per the Emission Directive using limiter plug tool (C).
NOTE : Engine WOT, and idle speed r/min in field
operation may vary from final adjustment
specifications due to changing ambient conditions,
fuel, and engine loads. Safe engine rpm variances
should be within the WOT, Idle speed ranges listed
in Section 1-1, otherwise the carburetor should be
readjusted.
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