Carburetor Common Adjustment Instruction
Adjusters and functions
1.Drain screw: used to drain the fuel out of the carburetor.
2.Idle mixture screw: controls the intake of fuel to adjust the engine for optimum running.
3.Idle speed screw: controls the intake of air to adjust the engine’s idle speed.
4.High speed screw: adjustment for high speed.
5.Low speed screw: adjustment for low speed.
6.Turn clockwise to decrease the RPM (revolutions per minute) while turning counterclockwise is for increasing the RPM. The amplitude for each adjustment is 1/4 turn.
Solutions for a “won’t start” problem after carburetor replacement
*1. Check if the cylinder assembly is leaking, start the engine up after adding some gasoline into the inlet, then listen carefully to whether there is gasoline firing in the cylinder.
2.Check if the ignition coil and spark plug are normal.
3.Check if the pressure hole of the gasket is aligned.
4.Check if the pump can pump fuel properly.
5.Check whether the fuel system or air filter are clogged. Follow the steps above, reassemble the parts, and your machine will work normally.
*Replace the intake O-ring in time if gasoline is leaking from O-ring.
*Remove the carburetor bottom cover and clean the float needle if the carburetor is still leaking after the engine stalling.
*Check the carburetor and ignition coil, if there is gasoline coming out from air filter after the engine stalling.
*Turn off the fuel valve after the engine shuts off.
*If the machine is going to be left for a long time, the gasoline in the tank should be emptied, the fuel valve should be turned off, and the gasoline in the machine should be discharged to avoid corrosion to the plastic parts of the carburetor by gasoline.
*Carburetor is made with very high requirements of precision and cleanliness, and cleanliness determines the working performance and lifespan of the carburetor.
*Pure gasoline is preferred, followed by E10 gasoline, to extend the lifespan of the engine.
*The fuel of 2-stroke engines is mixed fuel, and the ratio of oil and gasoline should comply with the requirements of the model manual.
Adjustments for 2-stroke butterfly valve diaphragm carburetors
1.Method to adjust idle speed and low speed: Start the engine and warm it up for 1 minute after installing a new carburetor. If the idle speed tends to surge up and down, then turn the low speed screw clockwise to its highest RPM(4500 to 5500r/min for reference) to fully fire the mixed fuel. Professionals can assure the RPM according to its sound, if the RPM is higher or lower, then turn counterclockwise the low speed screw to around 2800-3200r/min until turning the idle speed screw to the highest idle speed. Consistently pressing your trigger down to keep it running and flipping over your machine to simulate the working condition and check if it runs properly.
2.Method to adjust high speed: Pressing and holding your trigger down to run as fast as it can. Turn the high speed screw to a proper RPM(10500 to 12500r/min for reference). Consistently pressing your trigger down to keep it running and flipping over your machine to simulate the working condition and check if it runs properly.
3.Method to reset the carburetor in case of confused parameters during adjustment: turn the idle speed screw clockwise 1/2 to 1 turn; turn the low speed screw clockwise fully, and then turn counterclockwise for 1.25 to 1.75 turns; the high speed screw is also turned clockwise fully and then turn back for 1.5 to 2 turns.
Adjustment for 2-stroke rotary valve diaphragm carburetor
1.Method to adjust idle speed: Start your engine and warm it up for around 1 minute. If the idle speed tends to surge up and down, turn the idle speed screw to let its RPM stabilize around 2800 to 3200 r/min. Consistently press the primer bulb and check if the engine is going to stall.
2.Functions of the needle valve: If your machine is failing to reach the ideal idle speed by adjusting the idle speed screw, then fine tune the needle valve. Turn it clockwise to increase the fuel output while turn counterclockwise is to decrease the fuel output. This should only be done by professionals.
4.Method to adjust high speed: Pressing and holding your trigger down to run as fast as it can. Turn the high speed screw to let the RPM stabilize in an ideal range (9000 to 10000 r/min for reference). Carburetors without the high speed screw cannot be adjusted. Flip over your machine to simulate the working condition and check if it runs properly.
Adjustment for float carburetors
Solutions for the “won’t start” problem after carburetor replacement:
1.Check if the ignition switch is in the on position, the fuel valves of the fuel tank and carburetor are in the on position and the choke is closed when starting it up.
2.If there is a fuel pump in your machine, check if it can pump fuel normally and the cleanliness of the air filter and fuel filter.
3.Check whether the solenoid valve of the carburetor can be switched on and off normally.
4.Check if the ignition coil and spark plug are functioning normally.
5.Check if the cylinder is leaking, start the engine up after adding some gas into the inlet, then listen carefully to whether the fuel is firing from the cylinder
Idle speed screw adjustment: the RPM of idle speed surges when turning the screw clockwise; the RPM goes down when you turn the screw counterclockwise. The idle speed screw is for adjusting the idle speed of the engine (refer to the model manual for specific values).
Idle mixture screw adjustment: the mixture of gas and air tends to be thinner when turning the screw clockwise; the mixture tends to be thicker when turning the screw counterclockwise. Fine tune the screw if the engine has slightly running issues.