COPY
‑C3‑
Nov./29/ 12
How to Set the Carburetor
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Set the carburetor only after warming up the engine, and then test-drive. And use a plug with the right heat value.
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Do the setting in the following manner, studying at what throttle opening position the engine starts failing.
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Jet needle (Throttle position at 1/4 - 3/4)
Whether or not the engine revolution is in proportion to the throttle operation
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When the acceleration is not smooth or even, make the air-fuel mixture dense.
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Make the air-fuel mixture lean when the engine revolution goes up heavily and belches black gas.
The mixture ratio at this throttle position can be adjusted by the location of E-ring in the grooves.
The air-fuel mixture becomes dense as the location of the E-ring moves down from the 1st to the 5th groove.
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Main jet (The throttle position at 3/4 - 4/4)
The air-fuel mixture ratio at this throttle position can be adjusted by changing the number of the main jet.
The larger the main jet numbers, the
denser the mixture ratio becomes.
In view of the engine and muffler specifications, select the most appropriate main jet to get the highest
revolutions.
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Pilot jet (First of all, please adjust the air screw.)
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In case you have given more than three turns to the air screw to tighten it, use a pilot jet with a small number.
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If you have tighten the air screw (clockwise) to the full, use a pilot jet with a larger number.
Check whether you have made a right choice of the pilot jet by seeing if the engine starts up revolving s
moothly from the idling to running at slow speed.
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When the engine revolves up unevenly, the pilot jet number is too small. (At idle)
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When the motorcycle belches black exhaust gas and produces heavy exhaust sound, the pilot jet number
is too big. (At idle)
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After replacing the pilot jet, you need to readjust the airscrew.
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Air screw
The air screw adjusts the air mass flow at the time of engine’s revolving at slow speed. (At idling)
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Give the air screw a right turn
→
The air-fuel mixture gets dense.
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Give the air screw a left turn
→
The air-fuel mixture gets lean.
Loosen the tightened air screw back to the 1.5-turn position. And then from this position, give to the airscrew
a right or left turn of 1/4 to 1/2 till the engine revolves at the highest speed.
Loosen the idle stop screw till you get the steady idling revolutions. And once again adjust the position of the
airscrew to get the highest revolutions.
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On how the barometric pressure, temperatures and humidity affect the setting:
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At highlands or at high altitudes, the barometric pressure and air density go down and the air gets into the
carburetor in less amounts.
This makes the air-fuel mixture dense which was adjusted at low altitudes.
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Under the weather conditions with very low temperatures, the air density increases, which makes the
air-fuel mixture lean.
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Under the rainy and humid weather conditions, the air density decreases, which makes the air-fuel mixture
dense.
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Please be informed that, mainly because of improvement in performance, design changes, and cost increase,
the product specifications and prices are subject to change without prior notice.
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This manual should be retained for future reference.
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When the carburetor does not match the engine and the engine fails, the engine failures are caused by either too dense or too lean air-fuel mixture.
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The engine failure symptoms for the engine are as follows:
When the air-fuel mixture is too dense:
When the air-fuel mixture is too lean:
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The explosion sound with a dull thud continues intermittently.
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The engine malfunctions further if you use the choke.
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The engine malfunctions when you warm it up.
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The engine works well if the cleaner is detached.
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The motorcycle belches dense (or, black) exhaust gas.
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The plug smolders, getting blackened.
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The engine overheats somewhat.
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The engine starts working well If you use the choke,.
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The engine does not accelerate well. (No smooth acceleration)
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Revolutions change, generating weak power.
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The plug burns white.
1段目
4段目
2段目
5段目
1st groove
2nd groove
3rd groove
4th groove
5th groove
