7
SERVICE INFORMATION
HC-331ES
HC-341ES
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
fi
lter element must be clean and properly installed.
3. The muf
fl
er exhaust port must be clear of carbon.
4. The fuel lines, tank vent and fuel
fi
lter 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. The gear case assembly with blade set must be installed for proper engine loading.
B. Start and run engine for 3 minutes alternating rpm between WOT and idle every 10 seconds. Adjust
idle speed screw to 3,000 +/- 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 mixture needle(s) hole(s) to comply with Emission Directive.
2-2 Presetting Idle adjust screw, Idle mixture needle and Hi speed mixture needle
Parts Required : (2) limiter plug P/N P005-001270
1. Remove the plugs from idle mixture needle hole
(A) and hi speed mixture needle hole (B) using lim-
iter plug tool (C) as follows.
(1)Put limiter plug tool (C) on limiter plug in mixture
needle hole.
(2)Screw limiter plug tool anticlockwise 2 turns
slowly into limiter plug while pushing the tool.
(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 Idle mixture needle (D) and Hi speed mix-
ture needle (G) clockwise until lightly seated. And
then turn out both needles following turns.
Idle mixture needle : 2 1/2
Hi speed mixture needle : 1 1/2
3. Turn Idle adjust screw (E) anticlockwise until
the tip just touches throttle plate (F). Then turn it in
clockwise 2 3/4 turns.
NOTE :
Initial carburettor setting (Idle adjust screw,
Idle and Hi speed mixture needles) shown here is
to start the engine after restoration or carburettor
change. Idle adjust screw, Idle and Hi speed mix-
ture 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, variance would be ignorable.
(A)
(C)
(D)
(E)
(F)
(B)
(G)
(E)
(1)
(2)
(3)
